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HP 8341B User's Manual

1. i F EMI T t t TEH H 20 HH 45 GHz zd 4 HEH i 1 5 GHz 1 j i SE 20 GHz H 20 E c 40 US h wd i d 60 80 100 100 80 60 40 20 0 MODULATOR LEVEL dB Figure 3 31 Typical Unleveled Modulation Response HP 83408 418 Operating Information 3 103 POWER SEARCH Unleveled mode may also be accessed by pressing SHIFT INT The ENTRY DISPLAY now reads POWER SEARCH dBm and the INTERNAL annunciator comes on The power reading that appears is the same as the internal leveling power and it can be changed via keypad KNOB or STEP keys In this mode the instrument is unleveled as in the SHIFT METER mode but the microprocessor automatically searches out the correct power level This search occurs with each power entry change or frequency change and requires about 200 ms Once the search is co
2. Section III Operation P A e INTRODUCTION This section completely describes all front and rear panel keys connectors switches and displays of the HP 8340B 41B Synthesized Sweeper and explains all code mnemonics and the procedures used for HP IB programming Also described are enhancement procedures for the power control and modulation functions The descriptive material in the local operation subsection is organized according to the physical layout of the HP 8340B 41B To find specific information use as an index either Table 3 1 or Figures 3 1 and 3 2 Table 3 1 lists the operation modes and functions of the HP 8340B 41B shows the keystrokes that initiate those functions and lists the reference figures that explain the procedures Figure 3 1 is a front panel drawing of the HP 8340B with callouts indicating the reference figures that explain each key connector switch and display Figure 3 2 is a rear panel drawing of the HP 8340B with callouts that indicate the appropriate reference figures The nucleus for the HP IB programming material is Table 3 2 Table 3 2 lists all code mnemonics and provides cross referencing to equivalent front panel keys The codes that do not have an equivalent front panel key along with the HP IB programming procedures are explained following Table 3 2 The power control and modulation functions have severa
3. ad STANDBY LIT ON olo a 39g 566 206 0 SWEEP 9 MODULATION LEVELING acs RE OUTPUT rl Figure 3 13 Figure 3 12 Figure 3 15 Figure 3 14 Figure 3 16 Figure 3 17 Figure 3 1 Index by front panel keys display and connectors Figure 3 18 Figure 3 22 Figure 3 23 Figure 3 19 Figure 3 20 lt SWEEP 10uMz REF 1 E RU S up i js CD ET 9 EX Cc PEN LIFT sore pko OUTPUT oviFuT BLANK IN OUT E CON o 173 25 fe NQ NO OPERATOR SERYICEASLE PARTS INSIDE WARNING M TOR ABL s IM HOFER SERVICING TO TRALHED PERSORNE INTER ARS a 0900000000020 C n H sario gon Fine AROTECTION REPLACE Cc EEUEENETREN A do 09 477 0 MAX MM Figure 3 24 Figure 3 21 Figure 3 2 Index by rear panel connectors 0 3 4 Operating Information HP 8340B 41B Table 3 1 Index by Mode and Function 1 of 7 HP IB Reference Code Figure se ow Start Stop Sweep Center Frequency AF Sweep DF CW Frequency CW RESOLUTION SHIFT CW Mamo Turn On and S
4. HP 8340B HP 8341B SYNTHESIZED SWEEPERS HEWLETT PACKARD HP 8340B 41B SYNTHESIZED SWEEPERS Operating Information Copyright HEWLETT PACKARD COMPANY 1986 1400 FOUNTAINGROVE PARKWAY SANTA ROSA CA 95401 U S A Part of Operating Calibration and Assembly Level Service Manual Set HP Part Number 08340 90243 Printed AUGUST 1986 HP 8340B 41B Synthesized Sweepers Operating Calibration and Assembly Level Service Manual Set Operating Calibration and Assembly Level Service Manual includes Sections through P O VIII HP Part Number 08340 90243 Operating Calibration and Service Manual Microfiche includes Sections through P O VIII HP Part Number 08340 90244 Component Level Service Manual includes P O Section VIII HP Part Number 08340 90245 Component Level Service Manual Microfiche includes P O Section VIII HP Part Number 08340 90246 HEWLETT PACKARD SECTION TABLE OF CONTENTS INTRODUCTION 3 1 Reading HP IB Messages 3 93 Direct Writing to the HP IB Lines 3 95 LOCAL OPERATING INFORMATION Figure Page Figure Page ony ee Ee 9 3 25 HP IB 3 83 3 3 9 26 HP IB Handshake Timing 3 84 3 2 In dex Dy ded 3 4 3 27 Representative Status Registers 3 94 3 3 Power dBm Display 3 13 3 28 Representa
5. is the last used memory register to appear in the ENTRY DISPLAY then press a digit 1 9 to select the desired memory register Although the HP 8340B 41B is in the alternate mode the panel displays will only show the current front panel state The power level of the two alternated functions must have the same attenuator setting or the attenuator must be decoupled from the ALC automatic leveling control circuit which will allow up to 40 dB of power level difference This restriction is necessary to prevent rapid cycling and subsequent wear on the mechanical attentuator See PWR SWP in Figure 3 17 for an explanation of the attenuator and ALC relationship Press ALT again to cancel the alternate function SHIFT ALT saves the current frequency display multiplication factor as the instrument s default value In this mode pressing INSTR PRESET or turning power off and on will not affect the user defined frequency display multiplication factor Refer to the SHIFT START FREQ command in Figure 3 7 for more information This feature can be disabled by pressing SHIFT INSTR PRESET which sets the default muliplication factor to 1 and presets the instrument INSTR PRESET HP IB causes an internal self test of the HP 8340B 41B and initializes the instrument to a standard starting configuration 1 Start sweep at 10 MHz stop sweep at 26 5 GHz 20 GHz with HP 8341B 2 Power level set to 0 0 dBm however this level can be r
6. For example the clock commands for the HP 9826 9836 926 936 computers are 100 SET TIME 0 300 Clock TIMEDATE MOD 86400 210 PRINT TIME REQUIRED Clock For the HP 80 series computers the commands are 100 SETTIME 0 0 300 TIME 310 PRINT TIME REQUIRED C Other computers use similar commands HP IB PROGRAMMING TECHNIQUES FOR SPECIAL APPLICATIONS Although the preceding programming codes are sufficient for most applications it is possible to program the HP 8340B 41B at a fundamental level by directly manipulating signals on the HP IB lines The following material presents an introductory explanation of these specialized procedures first by briefly explaining the HP IB signal lines followed by the computer codes necessary for direct control of the HP IB lines HP IB PIN OUT DESCRIPTION Figure 3 25 shows a detailed view of the HP IB connector with a pin out description Notice that HP IB has 16 dynamic TTL level signal lines which can be categorized into three groups data lines handshake lines and system control lines The signal level on these lines is either TTL low a True condition TTL high a False condition or floating electrically disconnected 3 82 Operating Information HP 8340B 41B GND HP IB CONNECT TO RTN EARTH SRQ GROUND IFC NDAC NRFD DAV EOI NOTE The logic levels are TTL compatible ie true state 0 V dc to 0 4 V dc False State 2 5 V dc t
7. T6 Talker capable of basic talker serial poll and unaddress if MLA Talker Extended address no capability L4 Listener capable of basic listener and unaddress if MTA LEO Listener Extended address no capability SR1 Service Request complete capability RL1 Remote Local complete capability PPO Parallel Poll no capability DC1 Device Clear complete capability DT1 Device Trigger complete capability CO 1 2 3 28 Controller capability options CO no capabilities C1 system controller C2 send IFC and take charge send REN C28 send messages Et Electrical specification indicating open collector outputs These codes are completely in the IEEE Std 488 1978 document published by The Institute of Elec trical and Electronic Engineers Inc 345 East 47th Street New York New York 11017 Figure 3 20 HP IB Connector 2 of 2 Operating Information HP 8340B 41B HP 8410B C Interface Cable DESCRIPTION This connector interfaces the HP 8340B 41B to the HP 8410B C Network Analyzer Rear Panel Connector Interface Cable 8410 INTERFACE 14 25 000000000000 0000000000000 1 13 Connect the HP 8410B C Network Analyzer to this port on the HP 8340B 41B using a Source Control Cable HP Part Number 08410 60146 An Operating Guide at the end of this Section explains HP 8410B C to HP 8340B 41B interconnections This connector has pins that duplicate several rear panel f
8. CF AF markers and marker functions and the dB GHz slope function but the factor is not stored in the SAVE RECALL registers the current factor is used when recalling those registers Cancel the multiplication factor by pressing INSTR PRESET or enter a multiplication factor of 1 SHIFT ALT saves the current multiplication factor as the instrument s default value In this mode pressing INSTR PRESET or turning power off and on will not affect the user defined multiplication factor This feature can be disabled by pressing SHIFT INSTR PRESET which sets the default multiplication factor to 1 and presets the instrument Figure 3 7 Function Keys 1 of 3 HP 8340B 41B Operating Information STOP FREQ HP IB FB selects the stop frequency for start stop swept operation Press STOP FREQ then use either the rotary KNOB the STEP keys or the numerical keys with a terminator key to set the desired value The restrictions that apply to START FREQ also apply to STOP FREQ The stop frequency appears in the right FREQUENCY MHz display SHIFT STOP FREQ HP IB SHFB offsets the frequency displays by a fixed amount ranging from 500 GHz to 4 500 GHz This is used for example when the RF output of the HP 8340B 41B is connected to a mixer and for convenience the sum or difference frequency is shown in the displays Press SHIFT STOP FREQ then enter the desired offset value 500 GHz to 500 GHz follow
9. GHz GZ POWER LEVEL PL F 3 3 0 0 dB m DB 3 Combine the programming codes into an OUTPUT command For an HP 8340B 41B having address 19 this is the complete program 10 ABORT 7 20 CLEAR 7 30 OUTPUT 719 IPCH2 3GZPL 30DB 40 END ABORT CLEAR and IP are not always required but it is good programming practice to use them in this sequence because they place the HP 8340B 41B in a completely reset standard operating condition The HP 8340B 41B automatically upshifts lower case characters and ignores spaces and unas signed characters therefore line 30 in the preceding program could be written as follows resulting in enhanced readability at a slight cost in execution time 30 OUTPUT 719 CW2 3GHz PL 30 dB HP 8340B 41B Operating Information 3 59 Or the information could be written 30 OUTPUT 719 IP 40 OUTPUT 719 2 3 Gz 50 OUTPUT 719 PL 30 dB 60 END For interactive programs the frequencies power level and other numerical data can be placed in the OUTPUT statements as variables For example 30 OUTPUT 719 40 OUTPUT 719 CH 2 3 Gz 50 PRINT ENTER THE POWER LEVEL 60 INPUTP 70 OUTPUT 719 P DB 80 GO TU 50 90 END 3 60 Operating Information HP 8340B 41B Table 3 2 8340B 41B Programming Codes 1 of 4 Code Operation Performed Equivalent Key Ref Figure L E A1 Leveling intern
10. POWER LEVEL selects the external detector feedback voltage to which the HP 8340B 41B will attempt to level with a range of 6 2 00 V to 66 500 pV and a resolution of 0 1 dB The EXT INPUT BNC connector accepts either positive or negative inputs When in the SHIFT METER open loop mode the POWER LEVEL entry controls the linear modulator as explained in Figure 3 16 In any of these three modes the POWER dBm display shows the output power to the nearest 0 1 dB see Figure 3 3 for information on this display and its UNLEVELED indicator The output power can range from 110 dBm to a maximum value that depends on fre quency see Table 1 1 for power specifications Figure 3 17 explains PEAK PWR SWP and SLOPE power functions SHIFT POWER LEVEL HP IB SHPL selects the incremental step size for the STEP keys when they are used for the power level functions POWER LEVEL PWR SWP or SLOPE This is the LVL STEP function Press SHIFT POWER LEVEL then use either the rotary KNOB the STEP keys which step in a 1 2 5 sequence in this mode or the numerical keys with the dB m terminator key to set the desired step size The step size can range from 0 05 dB to 50 00 dB Consult Figures 3 3 and 3 17 for further information on power functions SWEEP TIME HP IB ST selects the sweep times for frequency sweeps or power sweeps power sweep is explained in Figure 3 17 Press SWEEP TIME then
11. setting ATTN 0 dB ALC 10 0 dBm gives plenty of headroom with enough depth available for 90 symmetric Available power can be maximized at a CW frequency by using the PEAK function Bandwidth for AM Applicaitons The small signal AM bandwidth extends from dc to a 3 dB frequency of atleast 100 kHz The actual upper limit is a direct function of the loop gain of the ALC loop The primary variable in the loop gain is the gain of the modulator which varies with both power level and frequency In general the modulator gain deviates the most from nominal at power levels just below maximum although at some frequen cies the gain will deviate at lower power levels because of non optimum YTM bias The latter is only a problem above 7 0 GHz The small signal 30 depth bandwidth may be expected to vary between 100 kHz and 300 kHz as power and or frequency is changed The bandwidth for greater depths is less At 9096 depth expect about 1 2 the 3096 bandwidth The above bandwidths are for internal leveling When external leveling with a crystal detector in its square law region the bandwidth is 1 2 of the internally leveled bandwidth at the same frequency and output power level With a crystal detector in its linear region the bandwidth is 1 4 The external leveling system is designed to provide linear AM when using a square law detector The RF output follows this law Vout Vo X Vin 1 HP 8340B 41B Operating Information 3
12. 100 mv 20 dBV gt amp 30 dBV 5 10 40 dBV 50 dBV i my HAHH H 60 dBV lt 66 dBV 70 dBV pm FH FH EE 80 dBV 40 30 20 10 0 10 20 30 DETECTOR INPUT POWER dBm Figure 3 33 Typical Crystal Detector Response at 25 C 3 106 Operating Information HP 8340B 41B f i Referring to Figure 3 29 it is seen that when externally leveled the POWER dBm display is stil connected to the internal detector of the HP 8340B 41B Thus it always tells the true output power regardless of external leveling setup This is a useful aid to determining if the external hardware is functioning properly In the above example if the POWER dBm display shows 40 dBm when the amplifier ouput is leveled to 10 dBm the user knows the gain is 30 dB As explained in the internal leveling section above the POWER dBm display is only accurate down to ALC levels of about 22 dBm below which it is intentionally blanked therefore that display is only useful if the ALC level is forced to be greater than 22 dBm This is done by inserting step attenuation until the display lights up again As still more attenuation is added the POWER dBm reading remains essentially constant as the external leveling loop holds the output level constant With each additional 10 dB step of attenua tion the ALC level jumps 10 dB until finally maximum available ALC level is rea
13. 120 PRINT STATUS REGISTER N 130 PRINT 140 FOR J 0 T07 150 PRINT BIT J BIT 5 22 160 NEXT J 170 PRINT 180 NEXTN Direct Writing to the HP IB Lines The final programming technique covered in this manual involves direct writing to the HP IB data handshake and control lines This is very advanced programming and should be attempted only by experienced programmers who are thoroughly familiar with the HP 8340B 41B and HP IB protocols Bus malfunctions or damage can result from errant applications of direct writing to HP IB lines Direct writing to the HP IB lines is accomplished by the CONTROL statement which has this syntax byte interface register select code number HP 9826 9836 interface register gt Q interface register register 9 The CONTROL statement ASSERT READIO WRITEIO are related statements used by some com puters is used to send information to the computer s control registers which have bit patterns that correspond to the HP IB lines The bit pattern of the control registers is computer specific Figure 3 28 shows representative control registers from the HP 9826 and HP 85A computers HP 8340B 41B Operating Information 3 95 3 96 Value 128 Value 64 Value 32 Value 16 Value Value 4 Value 2 HP 85A HP IB Control Registers Register Bit Number Defauit Register Number Value Fu
14. 140 ON INTR 7 GOTO 500 150 OUTPUT 719 PLEK 500 PRINT WARNING RF UNLEVELED Line 110 enables bit 2 only of status byte 1 which is the bit that causes an SRQ to be sent when any of the bits in status byte 2 change Line 120 enables bit 6 only of status byte 2 which detects an unleveled RF output Thus an unleveled RF is the only condition that will cause the HP 8340B 41B to send an SRQ Line 130 enables the computer s interrupt register that is associated with 1 port 7 and instructs the computer to monitor bit 3 decimal 8 for a true condition Bit 3 in this example is the SRQ RECEIVED bit but the actual bit depends upon the particular computer being used e g bit 2 for the HP 9826A 926 bit for the HP 85A Line 140 directs the program in the event of a true bit 3 which could occur if the power level is set too high line 150 allows operator adjustment of the power level via the rotary KNOB Once set several status byte bits remain latched until cleared by CS or CLEAR or until after the status bytes are read a second time The OS explanation describes all status byte bits 3 78 Operating Information HP 8340B 41B RS Reset Sweep causes the HP 8340B 41B to retrace to the start frequency If a sweep is in pro gress when an RS code is received the sweep will abruptly terminate and retrace In BASIC 100 QUTPUT 719 RS SFdt Step Frequency size sets the size of the frequency increment that can
15. 20 0 dB The above assumes a modulation waveform symmetric about 0 V For example Output power 19 0 dBm In coupled mode this results in ATTN 10 dB ALC 9 0 dBm Ninety percent modulation depth results ALC range of 9 0 dBm 5 6 dB 3 4 dBm maximum 9 0 dBm 20 dB 29 0 dBm minimum This is within the ALC limits at any frequency but the distortion may suffer due to operation below 20 dBm Using decoupled operation the desired output power may be set with ATTN 20DB ALC 1 0 dBm Then 90 depth swings the ALC from 6 6 dBm to 19 0 dBm The distortion will probably be better under these conditions if 6 6 dBm is available at the frequency of interest At some frequencies 20 dBm is available and setting ATTN 30 dB ALC 11 0 dBm may give a further improvement especially if attempting greater than 90 depth For minimum distortion the ALC should be used between 15 dBm and 15 dBm but not within 2 dB of maximum available power On HP 8340B s operating above 23 GHz the available output power is limited 1 dBm specified 3 dbm typical If the ALC is set close to 0 dBm the headroom available for modulation is limited Three dB excess power allows a maximum of 4096 peak modulation The available depth is not affected Decoupled mode may be used to advantage here For example in coupled mode an output power of 10 dBm results in ATTN 10 dB ALC 0 0 dBm Using decoupled mode
16. 41B is performing an analog sweep The LED is off during all of the following retrace band crossings band crossings occur at 2 3 GHz 7 0 GHz 13 5 GHz and in the case of the HP 8340A 20 0 GHz during the phase locking that occurs at the start frequency of each new sweep and each new band and during manual seeps since manual sweeps are synthesized RF ON DWELL is a time delay from when the instrument turns on its RF output to when the start of sweep occurs In CW mode this delay determines how long the instrument will wait after RF power is activated before allowing another change CW frequency This delay is set at the factor to 400us If the HP 8340B 41B is used with test equipment that requires a longer delay perform the following command Locally SHIFT MHz 1 7 Hz SHIFT kHz Hz Where is an integer value from 5 to 128 500us to 12 8ms To determine what value to enter for a given delay Value Desired Delay in microseconds 100 or Delay 100us per count in the value entry Via HP IB SHMZ17HZ SHKZ HZ Figure 3 11 Sweep and Trigger Keys 3 of 3 3 30 Operating Information HP 8340B 41B Instrument State Keys DESCRIPTION Instrument check and preset HP IB address assignment storage and recall of operating configura tions alternating operation and restoration of local control are the functions of this key group PANEL LAYOUT INSTRUMENT STATE INSTR O c
17. 65 For irregular frequency steps use a variable to represent the numerical data such as 100 1704 110 READ 120 OUTPUT 719 130 NEXT N 140 DATA 1 7 1 8 1E9 1E10 Line 140 contains the list of frequencies in Hz units hence 10 MHz 100 MHz 1 GHz and 10 GHz which are read in line 110 The semicolon beween the and A an artibrary variable in line 120 signifies to the computer that a terminator should not separate the code from the variable IF Increment Frequency is similar to the HP IB commands TRIGGER and GET group execute trigger IF must be used to trigger the SN function and can be used to increment SM and other CW frequency functions however IF cannot be used to trigger FP For example 100 OUTPUT 719 SF1G2 CW1G2 110 FORN 1TO 20 120 OUTPUT 719 130 NEXT N The step size and the starting CW frequency are both set to 1 GHz in line 100 Lines 110 to 130 cause the CW frequency to increment 20 times i e a 1 21 GHz stepped sweep IL123b Input Learn data is used in conjunction with OL Output Learn data to save recall various operating configurations of the HP 8340B 41B IL OL is similar to the SAVE RECALL functions except with IL OL the active function in use prior to OL storage is once again active after the IL restoration no function is active after a RECALL and there is virtually no limit to the number of instrument states that can be stored SAVE RECALL ha
18. For the sake of understanding observe a plot of unleveled flatness across the band of interest The number of ripples divided by sweep time gives the number of ripples per second which the leveling loop must remove The loop bandwidth must be several times this number in order to do so From the above it is apparent that the useable sweep time will depend on frequency range and RF hardware in use When using long cables there will be many ripples and their amplitude is dependent on the match at each end of the cable Inserting 10 dB of step attenuation greatly improves the source match when externally leveled thereby reducing the ripple amplitude For best stability of the leveling loop the video bandwidth of the external detector should be 100 kHz or more when XTAL leveling is selected The capacity of coaxial cables reduces the video bandwidth of crystal detectors A typical point contact detector HP 420 series 423A 8470A will work with up to 4 feet of 50Q coax on its output Typical HP low barrier schottky detectors HP 423B 8470B 3330 series will drive up to 40 feet of 50 Q cable The above paragraph applies to square law detectors with no dc offset Vout 0 for Pin 0 In METER mode the external leveling bandwidth is reduced to 0 7 Hz in order to allow operation with power meters Power meters have a very slow response due to thermal delay time and heavy elec trical filtering The 0 7 Hz bandwidth assures proper operatio
19. IB command statements s i 3 58 Operating Information HP 8340B 41B HP 8340B 41B PROGRAMMING CODES Table 3 1 lists the HP 8340B 41B programming codes arranged by function and Table 3 2 lists the codes alphabetically Notice in the Tables that several codes correspond to keys on the front panel of the HP 8340B 41B All front panel operations except the POWER switch can be duplicated by a remote computer program and those are the programming codes that are used to replace the key strokes There are also several programming codes listed in the Tables that are unique to HP IB operation The next two subsections describe all of these codes first by explaining how front panel operations can be duplicated and then explaining the unique HP IB operations Programs that Duplicate Front Panel Operations Any HP 8340B 41B operation that can be established by pressing keys on the front panel can be duplicated by a computer program with the exception of the POWER switch function This is the procedure 1 Determine the keystroke sequence needed for the desired operation For example this sequence establishes a 2 3 GHz CW signal at 30 dBm INSTR PRESET CW 2 3 GHz POWER LEVEL 3 dB m 2 Use the Information Cards located beneath the front panel or Tables 3 1 and 3 2 to find the programming code for each key Continuing with the example Key Programming Code INSTR PRESET IP CW CW 2 2 3 3
20. IS FUNCTIONS The most recently activated function and its present value is shown in this display In local operation the most recently pressed function key is the active function and will remain active until superseded by the pressing of another function key The HP 8340B 41B will remember for approximately three years or until the battery on the A6O processor board is changed the activated function even when the power is disconnected and will display that function in the ENTRY DISPLAY when the power is turned on The HP IB address HP IB ADRS 19 is displayed momentarily at power on followed by a display of the active function In local operation the active function can be changed by the rotary KNOB the STEP keys or the numerical keypad First press one of the function keys to make that function active and display its present value in the ENTRY DISPLAY Then change the value of that function by using either the KNOB the STEP keys or the numerical keys with a terminator key In remote operation the ENTRY DISPLAY will show the last function programmed ENTRY DISPLAY can be blanked turned off by pressing SHIFT CONT which turns off all of the displays The displays will remain blanked even when the function keys are pressed although the annunciators will change To regain a live display press SHIFT CONT again INDICATORS ENTRY DISPLAY contains two types of indicators amber identification annuncia
21. If the input is left open it pulls itself up to 1 8V which will turn the output on The HP 8340B 41B s delay and compression specifications assume an input of 0 to 3 0V which requires sinking about 1 6 mA and sourcing about 2 7 mA respectively The input accepts 12 V to 20 V with no damage which is compatible with the 6 V modulator drive of certain network analyzers Aside from small effects on delay and compression the waveform and amplitude of the input is unimportant as long as it transitions from 0 5 to 2 5 usor less This transition is sufficient to generate the fastest rise time Since the input is not linear input overshoot will not appear on the output 3 114 Operating Information HP 8340B 41B 5V PULSE INPUT Figure 3 36 Pulse Input Circuit Pulse Envelope The pulse envelope produced by the HP 8340B 41B is not a perfect rectangle rather it has finite rise time overshoot and video feedthrough Below 2 3 GHz the rise time and overshoot are essentially independent of frequency but above 2 3 GHz they are strongly influenced by the passband shape and centering of the HP 8340B 41B s tracking YIG filter Best envelopes are normally obtained by using the PEAK function The envelopes will change with frequency and slightly with power level Source Match In the absence of attenuation with a resistive pad a leveled microwave source generally provides a 50Q source match at its operating f
22. REGISTER to appear the ENTRY DISPLAY Press any digit 1 9 to select the storage register and the setting will be saved in that register The information stored in the memory registers is retained in memory indefinitely when ac line power is constantly available or for approximately three years without line power SHIFT SAVE HP IB SHSV is a save lock that prevents any new front panel settings from being saved SHIFT RECALL removes the save lock RECALL HP IB 0 9 retrieves a front panel setting that was previously SAVEd in storage registers 1 9 RECALL 0 retrieves the last entered front panel setting Press RECALL which will cause RECALL REGISTER to appear in the ENTRY DISPLAY Then press any digit 0 9 or use the STEP keys to select the desired memory register The rear panel 8410 CONNECTOR has a pin that duplicates the step recall function as explained in Figure 3 21 and the HP 8340A HP 8410 Operating Guide SHIFT RECALL HP IB cancels the save lock function which is described in the previous paragraph Figure 3 12 Instrument State Keys 1 of 3 HP 8340B 41B Operating Information 3 31 ALT HP IB AL1n n 1 9 turns on the function ALO turns off the function causes the instrument state to alternate on successive sweeps between the current front panel setting and the setting stored in memory location 1 9 Press ALT which will cause ALT WITH REGISTER
23. System Timing 3 82 3 32 Typical External Leveling Hookup 3 104 HP IB Programming Techniques for 3 33 Typical Crystal Detector Response Special Applications 9 82 3 106 HP IB Pin Out Description 3 82 3 34 Pulse Measuring System 3 112 The Twelve HP IB Lines 3 86 3 35 Error Detection and Modulator Drive 3 113 Computer Access of HP IB Lines 3 91 3 36 Pulse Input Circuit 3 115 Sending HP IB Messages 3 92 3 37 Video Feedthrough 3 116 HP 8340B 41B Table of Contents 3 1 3 2 SUPPLEMENTAL GUIDES OPERATING GUIDES Getting Acquainted with the HP 8340B 41B Synthesized Sweepers Using the HP 8340A Synthesized Sweeper with the HP 8755 Frequency Response Test Set Externally Leveling the HP 8340B 41B Synthesized Sweepers Using the HP 8340A Synthesized Sweeper with X Y Recorders Using the HP 8340A Synthesized Sweeper with the HP 8410B C Network Analyzer PRODUCT NOTES Increasing the Frequency Switching Speed on the HP 8340A Synthesized Sweeper List of other Product Notes PROGRAMMING NOTES Introductory Operating Guide HP IB for the HP 8340A 8341A Synthesized Sweepers with the HP 9000 Series 200 300 Desktop Computers BASIC Quick Reference Guide HP IB for the HP 8340B 41B Synthesized Sweepers IN CASE OF DIFFICULTY Table of Contents HP 8340B 41B
24. Table 3 3 The Standard ASCII Code 1 of 3 n ERA Octal Decimal Hexadecimal HP IB X0000000 000 00 X0000001 001 01 GTL X0000010 002 02 X0000011 003 03 X0000100 004 04 SDC X0000101 005 05 PPC X0000110 006 06 X0000111 007 07 X0001000 008 08 GET X0001001 009 09 TCT X0001010 010 0A X0001011 011 0B X0001100 012 0C X0001101 013 00 X0001110 014 0E X0001111 015 OF X0010000 016 10 X0010001 017 11 X0010010 018 12 X0010011 019 13 X0010100 020 14 DCL X0010101 021 15 PPU X0010110 022 16 X0010111 023 17 X0011000 024 18 SPE X0011001 025 19 SPD X0011010 026 1A X0011011 027 1B X0011100 028 1C X0011101 029 1D X001 0 030 1E X001 1 031 1F X010 0 032 20 LAO X010 1 033 21 LA1 X010 0 034 22 LA2 X010 1 035 23 X010 0 036 24 LA4 X010 1 037 25 LAS X010 0 038 26 LAG X010 1 039 27 LA7 X010 0 040 28 LAS X010 1 041 29 LA9 X010 0 042 2A LA10 i X010 1 043 2B LA11 X010 0 044 2 LA12 X010 1 045 2D LA13 X010 0 046 2E LA14 X010 1 047 2F LA15 0 X011 0 048 30 LA16 1 X011 1 049 31 LA17 2 X011 0 050 32 LA18 3 X011 1 051 33 LA19 4 X011 0 052 34 LA20 5 X011 1c 053 35 LA21 6 X011 0 054 36 LA22 7 X011 1 055 37 LA23 8 X011 0 056 38 LA24 9 X011 1 057 39 LA25 X011 0 058 LA26 HP 8340B 41B Operating Information 3 89 Table 3 3 The Standard ASCII Code 2 of 3 HP IB DIO LINES 0400023 x 20 o06000 wN xzs caom3ovozzrxc rommoou Q eVviA XXX X X XX
25. Tib b Test HP IB Interface verifies correct data transmission along the HP IB interface The pro cedure involves sending a data byte to the HP 8340B 41B then having the HP 8340B 41B return the same byte to the computer where the out going and incoming data is compared In BASIC 3 80 Operating Information HP 8340B 41B 100 FORN 0 255 110 OUTPUT 719 amp 120 ENTER 719 USING A 130 IF A lt gt N THEN GOSUB 500 140 NEXT N 150 PRINT TEST COMPLETED 500 PRINT TEST FAILED 510 PRINT TRANSMITTED N RETURNED 520 PRINT 530 RETURN The decimal numbers 0 through 25 cover all possible bit patterns for an 8 bit byte thus thoroughly exercising all 8 HP IB data lines and these numbers are concatenated onto the TI code in line 110 The image items in line 120 specify that EOL should be suppressed and that variable A an arbitrary variable should be filled with one byte of binary data B In line 130 a returned value that is less than or greater than i e not equal to the transmitted value signifies an HP IB test failure TLdt Time Limit constrains the minimum allowable sweep time The full sweep time range of the HP 8340B 41B is 10 milliseconds minimum to 200 seconds maximum although the minimum sweep time is frequency span dependent and cannot exceed a sweep rate of 600 MHz 1 millisecond This is a non warranted supplemental performance characteristic Also HP 8341B s equipped wit
26. accumulated by the HP 8340B 41B and are only cleared by an Instrument Preset or when the fault has been output following an OF command The outputted decimal number is interpreted at the bit level where the bits are defined as follows Bit 0 Not used Bit 1 Not used Bit 2 oscillator unlocked Bit 3 N2 oscillator unlocked Bit 4 YIG oscillator unlocked Bit 5 HET oscillator unlocked Bit 6 M N oscillator unlocked Bit 7 REF oscillator unlocked Bit 8 Notused Bit 9 Notused Bit10 LVC preset of level control board failed Bit 11 PEAK peaking algorithm failed Bit 12 ADC ADC time out Bit 13 KICK YO or SYTM kick pulse time out Bit 14 CAL calibration data checksum incorrect Bit15 Not used If any of these fault conditions are encountered consult the In Case of Difficulty section or Section VIII Service for further instructions A BASIC example 100 OUTPUT 719 110 ENTER 719 F 120 FORN 0 0 15 130 PRINT 140 NEXT N Line 130 determines each bit of arbitrary variable F in the BIT F N statement Ol 19a Output Identification outputs the revision date of the firmware presently loaded into the HP 8340B 41B as 08340BREV day month year 2 numbers for the day 3 letters for the month and 2 numbers for the year A BASIC example 10 DIMA I19 100 OUTPUT 719 01 110 ENTER 719 A 120 PRINT FIRMWARE REVISION A HP 8340B 41B O
27. and assigned to arbitrary variable A is always in the fundamental units of Hz dB m or seconds The Om code byte 2 can be used to determine the presently active function OB d Output next Band frequency indicates the frequency of the next bandcrossing Bandcross ings occur at 2 4 GHz 7 0 GHz 13 5 GHz and in the case of the HP 8340B 20 0 GHz A BASIC example 100 OUTPUT 719 6 2 110 OUTPUT 719 OB 120 ENTER 719 130 PRINT NEXT BANDCROSSING A 1E9 GIGAHERTZ In this example the HP 8340B 41B is outputting a 6 GHz CW signal so the next bandcrossing points is 7 0 GHz The OB frequency is always in Hz line 130 divides the OB value by 1 X 109 for conversion to GHz units OC 3d Output Coupled parameters allows the computer to read the values of the start frequency center frequency and sweep times in this order of the HP 8340B 41B The values are always read in the fundamental units of Hz and seconds In BASIC 100 OUTPUT 719 FA1GZ FB19GZ STAU 110 OUTPUT 719 Oc 120 ENTER 719 S C T 130 PRINT START FREQUENCY S 1E9 GHZ 140 PRINT CENTER FREGUENCY C 1E9 GHZ 150 PRINT SWEEP TIME T SECONDS The computer would display for this example a start frequency of 1GHz a center frequency of 10 GHz and a sweep time of 0 030 seconds HP 8340B 41B Operating Information 3 67 OD Output Diagnostic values allows the computer to read the values that result from the diagnos
28. as shown in the POWER dBm display The ALC value should be as close as possible to 20 dBm to achieve the widest span power sweep 4 Setthe SWEEP TIME as explained in Figure 3 7 5 Press PWR SWEEP and POWER SWEEP x xx db SWP where x is the last entered value will appear in the ENTRY DISPLAY Use either the KNOB the STEP keys or the numerical keys with the dB m terminator key to select the span of the power sweep positive values only ranging from 0 0 to 40 00 dB SWP 6 Select SWEEP and TRIGGER as described in Figure 3 11 If only narrow span power sweeps are necessary the ATN does not need to be decoupled from the ALC Omit steps 2 and in the preceding text using instead the POWER LEVEL key to set the initial power output This simplified procedure restricts the range of power sweeps to that of the coupled ALC which is 9 95 dBm to the maximum power permitted maximum power depends on frequency as listed in the Specification Tables SHIFT PWR SWEEP HP IB SHPS decouples the attenuator ATN from the automatic leveling control ALC as explained in the preceding function Recouple the ATN and ALC by pressing POWER LEVEL SLOPE HP IB SL1 turns on the slope function SLO turns off the function compensates for sys tem or cable losses at high frequencies by linearly increasing the power output as the frequency increases Press SLOPE RF SLOPE xx xx dB GHz where x is the last entered
29. be stepped by UP or DN equivalent to the up down front panel STEP keys The SF code is equivalent to the SHCF code and both are equivalent to the SHIFT CF keystroke operation as described in Figure 3 7 The SF step size can be as small as 1 Hz as large as 10 GHz or it can be coupled to the AF frequency span with the AU auto code the coupling is explained in Figure 3 7 A BASIC exam ple 100 OUTPUT 719 SF 1 MZ 110 OUTPUT 719 400 MZ 120 FORN 1TO 200 130 OUTPUT 719 UP 140 NEXT N 150 GOTO 110 This program sets the step size to 1 MHz establishes a starting CW frequency of 400 MHz then performs a 400 600 MHz discrete sweep SG Single sweep is identical to the S2 code and both are equivalent to the front panel SINGLE key which is described in Figure 3 11 SG causes the HP 8340B 41B to perform single sweeps and is used in conjunction with the TRIGGER codes T1 T2 and T3 If trigger code T1 FREE RUN is in effect the SG code or the TS code is output every time a single sweep is needed If SG is output in the middle of a sweep the sweep will abruptly terminate and retrace A BASIC example 100 OUTPUT 719 IP SG T1 110 PRINT PRESS CONTINUE TO START THE SHEEP 120 PAUSE 130 OUTPUT 719 Sc 140 GOTO 120 SMdt Sweep Manual is identical to the S3 code and both are equivalent to the front panel MANUAL key which is described in Figure 3 11 SM is used by first establishing the start and sto
30. controls are disabled The preceding ENTRY OFF paragraph contains additional information about this indicator Figure 3 8 KNOB STEP Entry 2 of 2 HP 8340B 41B Operating Information 3 23 Frequency Marker Keys DESCRIPTION This key group selects the five markers the marker functions MARKER SWEEP MARKER DELTA and MARKER TO CENTER FREQUENCY and several diagnostic functions that are used during servicing PANEL LAYOUT FREQUENCY MARKER ALL OFF 9 ON OFF ON OFF FUNCTIONS M1 M5Y HP IB Mh1 M5 keys select markers 1 5 Press one M1 M5 key and the present value of that marker will appear in the ENTRY DISPLAY Use either the rotary KNOB the STEP keys or the numerical keys with a terminator key to set the desired marker frequency Repeat this process for the other markers as needed If the initial marker frequency is outside of the current sweep range a slight turn of the KNOB will bring the frequency of that marker to the center fre quency of the sweep markers are normally displayed as z axis intensity dots but can be changed to amplitude dips an abrupt discontinuity in the sweep trace by pressing AMTD MKR as explained in Figure 3 17 The markers are functional whenever their individual LEDs are lighted however only one marker can be active at a time the active marker is shown in the ENTRY DISPLAY and can be changed via KNOB STEP keys or numerical keys with a terminator key Press
31. expression DATA string expression primary address TALK C LIST address secondary address UNL A MTA 3 92 Operating Information HP 8340B 41B The secondary command DATA sets the ATN line False all other secondary commands CMD TALK LISTEN UNL MLA and MTA set ATN True Information accompanying the SEND statement can be either ASCII encoded characters that correspond to the HP IB functions see Table 3 3 or computer recognized mnemonics For example to read the status bytes from the HP 8340B 41B the HP IB sequence is UNL MLA the computer s TAD HP 8340B 41B s SPE data bytes SPD UNT This sequence is accomplished in BASIC by using either computer recognized mnemonics 100 SEND7 UNL MLA TALK 19 CMD 24 110 ENTER 7 USING B S 120 SEND7 CMD25 UNT where CMB 24 is SPE and CMD 25 is SPD or the same sequence can be accomplished using ASCII encoded HP IB information 100 SEND 7 CMD 5S amp CHR C24 110 ENTER 7 USING B S 120 SEND7 25 In line 100 is the ASCII code for UNL 5 is a representative MLA and S is TA19 In line 120 underscore is the ASCII code for UNT In both examples the ATN line is set True or False by the computer depending on the context of the mnemonics and does not require any specific commands This is an illustrative example only status bytes can be more easily read using
32. in the manual of other instruments Here is a demonstration program for the HP 9826 9836 926 936 series of computers 10 REMPRINT THE CRT NOT THE LINE PRINTER 20 PRINTER IS 1 30 OUTPUT 719 IP CWI 62 40 ON KNOB 075 GOSUB 60 50 GOTO 50 60 Count KNOBX 70 PRINT KNOB COUNT Count 80 OUTPUT 719 RB amp CHR Count 90 RETURN 100 END Line 30 establishes CW as the active function with an initial value fo 1 0 GHz ON KNOB in line 40 instructs the computer to detect any rotation of the knob The computer s knob generates 120 pulses per revolution when the first pulse is detected line 40 starts a sampling time clock 75 milliseconds in this example and branches to the subroutine located at line 60 HP 8340B 41B Operating Information 3 77 KNOBX in line 60 counts the pulses that occur in the sampling time interval the sampling time range is 0 01 2 55 seconds but the sampling time must be short enough to keep the pulse count in the range of 127 to 128 and assigns the value of that count to arbitrary variable Count Line 70 displays the pulse counts on the computer s CRT pulse counts of 1 30 are typical for this sampling time Line 80 sends the pulse count information to the HP 8340B 41B where it affects the active function CW in this example In line 80 the pulse count is converted from decimal to binary by the CHR function and concate nated to the RB code One byte of numerical data can accompan
33. indicate the power output only when the HP 8340B 41B is internally leveled and is not being amplitude modulated AM by a modulation signal containing a dc compo nent Under these conditions the values of PLOA OPPL and OR will agree to within the toler ances of the measuring circuits 0 1 dB OR can always be used to measure power output and must be used whenever any of these conditions exist 1 The HP 8340B 41B is unleveled for any reason 2 the instrument is being amplitude modulated by a modulation signal having a dc component 3 the HP 8340B 41B is being externally leveled A BASIC example 100 OUTPUT 719 110 ENER 719 P 120 PRINT POWER LEVEL P DBM OS 2B Output Status bytes is used to read the two 8 bit status bytes from the HP 8340B 41B The first status byte concerns the cause of an SRQ Service Request while the second status byte concerns failures and faults as follows HP 8340B 41B Operating Information 3 75 3 76 STATUS BYTE 1 SRQ on REQUEST SRQ on RF New fre SERVICE Settled Changed in Numeric Any Front quencies RQS Extended Entry Panel Key or Sweep Status Completed Pressed Time in Byte HP IB or Front External Oven Cold Self Test Freq Ref Modulation Failed Selected Status Byte 1 Bit 0 SRQ caused by a key closure on the front panel of the HP 8340B 41B use the OM code to determine the front panel status Bit 1 SRQ cau
34. inputs Since crystal detectors lose sensitivity at low power levels the detector provides an accurate power indication for ALC levels down to 10 dBm and is acceptable 1dB down to 20 dBm The maximum amount of power available from the level control circuits varies with RF frequency from 1 dBm specified at 26 5 GHz HP 8340B only to typically 21 dBm at 4 5 GHz therefore the level control circuits can provide continuous control of ALC levels over a maximum span of approximately 20 dBm to 20 dBm Coupled Mode Since many applications require power levels less than 20 dBm a step attentuator is provided that has a range of 0 to 90 dB in 10 dB steps Thus power levels down to 110 dBm is achieved when the attenuator and ALC work in conjunction Because of the attenuator the ALC will normally be used over only a portion of its 40 dB range Since accuracy suffers below 10dBm and at some HP 8340B frequencies only 1 dBm is available the ALC is normally set between 10 and 0 dBm To get power less than 100 dBm the attenuator is left at 90dB and the ALC used from 10to 20 dBm however the ALC accuracy and noise performance is degraded at this level and is the reason that some specifications apply only down to 100 dBm At frequencies where power levels above 0 dBm are desired the attenuator is left a 0 dB and the ALC used from 0 to 20 dBm or whatever power is available at the RF frequency in use The p
35. is recommended cleaning by vacuuming or washing and drying is recommended only if a replacement filter is not available Section VI Replace able Parts contains a complete parts listing for the fan in the B1 Fan Assembly pictorial Figure 3 23 Assembly 3 50 Operating Information HP 8340B 41B Power Line Module DESCRIPTION The line power module contains a safety fuse and a removable cam that is used as a switch to match the HP 8340B 41B s power supply to the locally available ac power CAUTION Do not attempt to rotate the voltage selector cam while itis installed in the line module or non repairable damage will result The cam must be completely removed from the line module rotated to the proper posi tion and reinstalled Refer to the instructions below Replacement of fuse Pry open line module cover door Pull out fuse carrier Insert fuse of proper rating Place carrier back into line module gt Selection of Operating Voltage 1 Pry open line module cover door 2 REMOVE CAM FROM THE LINE MODULE 3 Rotate the cam to the desired voltage When the line module cover is closed the selected voltage will be visible through a small window 4 Insert the cam back into the line module Close the line module cover door The HP 8340B 41B requires a maximum of 500 VA of electrical power 40 VA in STAND
36. kHz bandwith Press XTAL and xx dB REF xx xx dBV where x is the last entered value will appear in the entry display Then use the rotary KNOB or the numerical keys with the dB m terminator key to change the REFerence level and the STEP keys to change the ATN while watching either the POWER dBm display allowing for losses in the coupler or splitter or an attached power meter The Externally Leveling the HP 8340B 41B Synthesized Sweeper operating guide located at the end of this section fully explains crystal leveling and shows typical equipment interconnections SHIFT XTAL HP IB SHA2 activates the external source module leveling mode A portion of the mm wave signal from the HP 83550 series mm wave Source Module is detected and delivered to the EXT INPUT BNC connector thus forming an output input feedback loop Press SHIFT XTAL and EXT MODULE POWER xx xx dBm will appear in the entry display Enter the desired externally leveled module power using either the KNOB STEP keys or numeric keypad Terminate with the dBm key Figure 3 16 Leveling Keys Input 1 of 2 HP 8340B 41B Operating Information 3 37 3 38 METER HP IB selects external power meter leveling of the HP 8340B 41B A portion of the RF output must be measured by a power meter with the power meter also connected to the EXT INPUT BNC connector to form an output input feedback lo
37. retained in memory and will be recalled when that marker key is pressed once again A deactivated marker will not affect the MKR SWEEP MKR A or MKR CF functions SHIFT OFF HP IB SHMO turns off deactivates all markers M1 through M5 However the frequency values of all markers are retained in memory and will be recalled when the marker keys are pressed once again Deactivating the markers will not affect the SWEEP MKR A or MKR CF functions A HP IB MD1 turns on the function MDO turns off the function causes the frequency difference between any two markers to appear in the ENTRY DISPLAY Press any two marker keys M1 M5 then press MKRA and the ENTRY DISPLAY will show the frequency difference Press any other marker keys M1 M5 and the ENTRY DISPLAY will change to show the frequency difference between the two most recently passed markers a display the trace between the two selected markers is intensified intensity markers only not AMTD MKR The LED above MKRA shows when the function is on lighted or off not lighted SHIFT has no effect on the HP 8340B 41B MKR CF HP IB sets the center frequency of the sweep to the frequency of the active marker Press any marker key M1 M5 then press MKR CF to change the center frequency of the sweep to that of the marker The frequency span AF will not change unless the new s
38. set the desired CW value as described in the preceding paragraph Then press SHIFT CW and observe the flashing cursor in the ENTRY DISPLAY which identifies the digit presently affected by the rotary KNOB Reposition the cursor by pressing either the left arrow or right arrow STEP key the arrows are printed in blue above the STEP keys When the cursor is positioned over the desired digit press CW to return to CW mode After changing the CW RES FIXD appears in the right corner of the ENTRY DISPLAY However the CW RES can be coupled to theAF frequency span AUTO in the ENTRY DISPLAY by pressing SHIFT CW AUTO which causes the CW RES to be 1 1000 of the frequency span reduced to the Figure 3 7 Function Keys 2 of 3 3 20 Operating Information HP 8340B 41B next lowest integer power of ten for example a frequency span of 16 GHz corresponds to CW RES of 16GHz 1000 16 MHz 16 MHz reduced to the next lowest integer power of ten equals 10 MHz which is the CW RES For frequency spans less than 1000 Hz the AUTO CW RES is 10 Hz AUTO is the default condition for CW RES after an INSTR PRESET POWER LEVEL HP IB PL controls the output power level of the HP 8340B 41B when it is internally leveled Press POWER LEVEL then use either the rotary KNOB the STEP keys or the numerical keys with the dB m terminator key to set the desired value resolution 0 05 dB When externally leveled
39. suppresses the normal end of line sequence by using the image specifier this must be done in case the bit pattern of the data coincidentally duplicates the bit pattern of the EOL which would cause a false termination and inputs the 8 bytes of data image specifier B indicates binary data Lines 120 190 prints the bytes decimal and bit values This is how to interpret the byte data BYTE 1 indicates the last pressed front panel key and the decimal value of this byte corresponds to the keys as follows Decimal Value Decimal 0 9 numerical keys 82 RECALL ALT minus key not used BACK SPACE PULSE used as the back space AM ENTRY OFF v MKR CF not used SHIFT MKR SWEEP START FREQ INSTR PRESET STOP FREQ not used CF CONT AF SINGLE 101 CW 102 POWER LEVEL 103 SWEEP TIME 104 SHIFT 105 GHz dB m 106 MHz sec M4 107 kHz msec M5 108 Hz AUTO FREE RUN 109 INT LINE EXT 110 XTAL MKR SWEEP 111 METER OFF 112 AMTD MKR MKRA 113 PEAK not used 114 PWR SWP 115 SLOPE LOCAL 116 RF SAVE 117 128 not used HP 8340B 41B Operating Information 3 71 Decimal Value Note Although all possible shift key combinations are listed some of these combinations have no effect on the
40. synchronization with the ac power line frequency which is typically 50 or 60 Hz SHIFT LINE HP IB SHT21 enables penlift SHT20 disables penlift generates a penlift signal at each band crossing When an HP 8340B 41B sweep crosses frequency bands the RF is momentarily turned off at each band crossing which can cause a negative spike on X Y recorders To prevent the negative spike SHIFT LINE activates a rear panel PENLIFT OUTPUT connector that causes the X Y recorder s pen to lift at each band crossing The PENLIFT function works only when the sweep time is gt 5 seconds See Figure 3 18 for information on the rear panel connector and the X Y Recorder Operating Guide at the end of Section III for specific information on X Y recorder interconnections EXT HP IB T3 externally triggers the sweep function Figure 3 18 explains the rear panel EXT TRIGGER INPUT connector and the trigger signal requirements SHIFT EXT HP IB SHT3 activates the oscillator function When the red UNLK annunciator appears in the ENTRY DISPLAY press SHIFT EXT which will cause 5 REF M N HET YO N2 N1 to appear in the ENTRY DISPLAY The flashing cursor indicates which oscillator circuit is not phase locked with the remedy found in the appropriate part of Section VIII Service Press SHIFT M5 to cancel this diagnostic function and to return the displays to their previous condition INDICATORS SWEEP green LED lights when the HP 8340B
41. this status byte has been read or until cleared by the CS or CLEAR 719 commands Bit 5 AC line power interruption has occurred since the last Instrument Preset This bit also remains latched until read or cleared Bit 6 RF is unleveled use OR to determine present power level This bit also remains latched until read or cleared Bit 7 FAULT annunciator is on seen in the ENTRY DISPLAY of the HP 8340B 41B Use OF to determine the cause of the fault A BASIC example 10 REMCLEAR CRESET TO ZERO BOTH STATUS BYTES 20 OUTPUT 719 CS 100 QUTPUT 719 OS 110 ENTER 719 USING B S1 52 120 5 51 130 1102 140 PRINT STATUS BYTE 150 FORN 0T07 160 PRINT BIT N BITSCS ND 170 NEXT N 180 5 52 190 NEXTK Line 110 is a formatted I O statement where suppresses the end of line sequence to avoid misinterpreting valid data as an EOL sequence and B indicates that each of the following vari ables arbitrary variables S1 and S2 should be filled with one byte of information Line 160 deter mines each bit of the status bytes status byte 1 first S 51 N 0 to 7 then status byte 2 S S2 N 0 to 7 Programming codes RM and RE explain how the status bytes can be masked RBb Remote knoB allows the rotary knob of other instruments computers network analyzers to control the active function of the HP 8340B 41B The knob is sometimes called an RPG rotary pulse generator or cursor wheel
42. to remote pro gram control The HP IB sequence REN UNL LAG clears the REMOTE message and causes the listening instruments to return to local control The HP IB sequence UNL LAG REN GTL prevents an instrument over ride of remote control The front panel LOCAL key is inoperative and only the controller or a hard reset by the POWER switch can restore local control The sequence REN LLO causes all instruments on the bus to be removed from local lockout and to return to local control The HP IB sequence SRQ can be sent by an instrument at any time to signify that attention is required from the controller The HP IB sequence SRQ The SRQ is held true until the instrument no longer needs service or until a poll is conducted to determine the nature of the SRQ is an 8 bit byte of information from an addressed instrument with each bit signifying the status of a specific instrument The HP IB sequence UNL LAD SPE databyte CR LF ATN SPD is a parallel poll of the bus instruments The HP 8340B 41B does not respond to parallel polling transfers active control of the bus from one controller to another The HP IB sequence ATN UNL TAD TCT terminates all bus transactions and causes all instruments to listen for a command from the controller The HP IB sequence IFC REN This completes the 12 HP IB messages Operating Information HP 8340B 41B
43. use either the STEP keys which increment in a 1 2 5 sequence for sweep time the rotary KNOB or the numeric keys with the sec or msec terminator key to set the desired value Sweep time has an allowable range of 10 msec to 200 seconds but the fastest sweep time is constrained by the frequency span The sweep rate cannot exceed 600 MHz msec 300 MHz msecfor HP 8341B Option 003 for example the full 26 49 GHz frequency span of the HP 8340B be swept no faster than 26490 600 44 15 msec The fastest possible sweep can be determined automatically Press SWEEP TIME AUTO to obtain the fastest possible calibrated sweep time for any sweep span The right hand corner of the ENTRY DISPLAY shows AUTO when the sweep time is coupled to the frequency span or FIXD when sweep time is independent AUTO is the default condition after INSTR PRESET Also see TL in the HP IB section SHIFT SWEEP TIME HP IB SHST places the HP 8340B 41B into CF AF sweep mode with AF controlled only by the STEP keys and CF controlled by either the rotary KNOB or the numerical keys with a terminator key This is the ZOOM function which allows the operator to quickly zoom in on a frequency band of interest even from very wide sweeps SHIFT HP IB SH activates functions that are printed in blue on the front panel as well as special functions All SHIFT functions are described in this Operation chapter and are summarized on the two
44. volt input to off 1 volt input ratio is a function of power level and frequency but is always greater than 20 dB The amplitude of the RF output changes linearly as the AM input changes from 1 to 1 volts The specifications given in Section list all electrical requirements of the AM input and explain the subsequent effects on the RF output Damage level for this input is 2 12 volts or lt 12 volts FM MODULATION INPUT accepts a 8 volt to 8 volt signal when on the 1 MHz Volt sensitivity or a 1 volt to 1 volt signal when on the 10 MHz Volt sensitivity Any signal greater than these limits will cause distortion The deviation changes linearly as the FM input changes from 0 to its upper or lower voltage limit The rate is determined by the frequency of the FM input signal Table 1 1 lists relevant specifications Damage level for this input is 29 volts or lt 9 volts Figure 3 15 Modulation Inputs 3 36 Operating Information HP 8340B 41B Leveling Keys Input DESCRIPTION Internal or external crystal or power meter power leveling is selected by these keys which also select a band crossing diagnostic and allow direct linear modulator access The external leveling BNC input connector is also described in this Figure PANEL LAYOUT PHA MODULE SEARCH amp EXT INPUT XTAL LEVELING FUNCTIONS EXT INPUT BNC connector is the input port for an exter
45. 109 3 110 This applies also to internal leveling When externally leveled with a linear detector the relationship is Vout Vo X Vin 1 2 power meter is a square law detector so AM with power meter leveling is linear For bandwidth see the external leveling secton For simultaneous AM and pulse modulation see the next section PULSE MODULATION The HP 8340B 41B provides leveled pulse modulation over a wide range of pulse widths and rates Characteristics such as leveling accuracy and response time vary with pulse width pulse rate tem perature power level and RF frequency In order to use the pulse leveling system to best advantage it is helpful to understand its operation and limitations Sample and Hold Leveling The basic leveling loop was previously explained with reference to Figure 3 29 Fundamental to its operation is the internal detector which measures the RF amplitude The leveling performance is limited by the accuracy of this measurement The most difficult aspect of leveled pulse modulation is measuring the amplitude of a very narrow RF pulse Figure 3 34 is a block diagram of the detector circuitry with waveforms Trace 1 is the pulse modula tion input signal to the HP 8340B 41B It controls a fast RF modulator which is either full on or full off The amplitude when on is controlled by the linear modulator used for CW leveling and AM Trace 2 is the resultant RF pulse which is the HP 8340B 41B s output This p
46. 1238 A 150 REM 160 REM RETRIEVE THIS INSTRUMENT STATE 170 OUTPUT 719 IL amp A Line 140 is a formatted I O statement where the suppresses the end of line sequence so valid data is not misinterpreted as EOL and the 123A is an instruction to fill A with 123 bytes of literal data Line 170 concentrates the literal data in A which is an arbitrary variable with the IL pro gramming code For additional I O formatting information consult the 1 Programming Manual for the specific computer being used OM 8b Output Mode outputs 8 bytes of information that completely describes the presently active function of the HP 8340B 41B Byte 1 records the last pressed front panel key Byte 2 indicates the active function Byte 3 records the active and previously active markers Byte 4 indicates the marker status Byte 5 indicates trigger sweep and frequency modes Byte 6 indicates the status of various front panel functions Byte 7 indicates output power and leveling status Byte 8 indicates the status of the modulation and other functions 3 70 Operating Information HP 8340B 41B BASIC example 10 DIMBCS8 100 OUTPUT 719 OM 110 ENTER 719 USING B BC1 BC2 BC3 BCD BCS BCG BC7 BC8 120 F RJ 1to8 130 PRINT BYTE J 440 PRINT DECIMAL BCJ 150 FORK 0T07 160 PRINT BIT K BITCBC D K D 170 NEXT 180 PRINT 190 NEXT J Line 110
47. 2 dBm 42 dBm etc depending on the attenuator setting Decoupled Mode In some applications it is advantageous to control the ALC and attenuator separately achieving combinations of settings which are not available in the coupled mode Press SHIFT PWR SWP to achieve decoupled mode which causes dB ALC to show the ENTRY DISPLAY The ALC setting is entered via keypad or KNOB while the attenuator is incre mented with the STEP keys As before the POWER dB display indicates the true composite output power Note If an entry is made in decoupled mode and subsequently POWER LEVEL is pressed the HP 8340B 41B reverts to coupled mode It will set itself to the same power level but the attenuator and ALC settings may be different One use of decoupled operation is power sweep where the output power linearly tracks the sweep voltage ramp The HP 8340B 41B can generate power sweeps of up to 40 dB depending on fre quency The power at the start of the sweep is set via POWER LEVEL coupled operation or SHIFT PWR SWP decoupled operation and the sweep range the amount the power increases during the sweep is entered by pressing PWR SWP followed by the desired dB sweep value If the sweep range entered exceeds the ALC range stop power greater than maximum available power the UNLEVELED annunciator will light at the end of sweep No warning is given a
48. 3 14 3 15 Pulse Modulation Frequency Modulation 3 6 Operating Information HP 8340B 41B Table 3 1 Index by Mode Function of 7 HP IB Reference Code Figure Step Size Display and Entry Control sae FREQUENCY STEP SHIFT CF SF or SHCF 3 7 EAM te SHIFT POWER LEVEL SP or SHPL i 1 STEP Ken uP 3 8 me ele KEN PNE ENABLE PENLIFT 8 SHT21 3 11 AT BANDCROSSING SHIFT LINE DISABLE PENLIFT AT BANDCROSSING SHT20 Fixed Function To Coupled Mode AUTO Hz AUTO AU 3 10 IR RETAIN MULTIPLI CATION FACTOR AT ON OFF OR INSTR SHIFT ALT SHAL PRESET 3 12 DISABLES SHIFT ALT MULTIPLI CATION FACTOR PRESETS TO 1 Display Offset OFFSET FACTOR SHIFT STOP FREQ SHFB 3 7 Instrument State Registers instrument Preset INSTR PRESET INSTR PRESET Save Instrument State SAVEn SAVE Recall An 3 12 Instrument State RECALL n RECALL Lock Registers SAVE LOCK SHIFT SAVE SHSV Unlock Registers SAVE UNLOCK SHIFT RECALL SHRC X Y Recorder Interface Active Function Frequency Display Scale SHIFT INSTR PRESET SHIP HP 8340B 41B Operating Information 3 7 Table 3 1 Index by Mode and Function 4 of 7 18 Reference Instrument State Registers Cont d ALT ON ALT ALT OFF ALO ERASE RAM set all variables and
49. 6 32 63 and bits 6 7 False This completes the HP IB programming information HP 8340B 41B Operating Information 3 97 USING THE 8340B 41B POWER CONTROL AND MODULATION SYSTEMS The preceding explanations of the power control and modulation functions are sufficient for the majority of applications however to extract the utmost performance from this instrument the follow ing special information might be helpful INTERNAL LEVELING The RF Output is controlled by the automatic level control ALC circuit otherwise referred to as the leveling loop Figure 3 29 shows a simplified diagram of this system The leveling loop is a feedback control system in which the output power is measured and compared to the desired level If the two are not equal the loop changes the output until they are equal The two inputs labeled INPUTS convey the desired power level One of these is a voltage derived from the power value shown in the ENTRY DISPLAY In the absence of modulation this voltage is used to set the output power level The amplitude modulation AM input causes the output to increase or decrease relative to this level The pulse modulation input is essentially an ON OFF switch not an ALC input The RF power level from the level control circuits is referred to as the ALC level and is measured by a crystal detector The DC output from this detector is fed back to the level control circuits for comparison with the ALC
50. ATOR SL LO CONTROL 10dB ZN LO FEED LO LEVEL THROUGH 1 dBm DETECTOR DETECTOR 5dBm IF MEASURES 2dBm MEASURES 15dBm ALC LEVEL REVERSE POWER Figure 3 30 Reverse Power Effects Operating Information 3 101 HP 8340B 41B When using decoupled mode to set low ALC levels some caution is necessary At ALC 20 dBm the amplitude accuracy degrades by 1 dB This results from temperature induced drift in the detection circuitry Some spurious signals such as ac power line related sidebands are worse at 20 dBm and may exceed specifications which do not apply at ALC 20 dBm Despite its level uncertainty the output power at ALC 20 dBm is more stable than a normal power meter In checking the output care must be taken to zero the meter with the HP 8340B 41B s RF turned off Pressing the sensor zero button on a power meter does not assure that it is zeroed since the display on some meters is blank for inputs below 30 dBm when in the dBm mode Selecting the WATT mode keeps the display alive and the user can then see if the meter is really zeroed press the zero button several times if necessary When the HP 8340B 41B s heterodyne band 01 to 2 3 GHz is in use approximately 30 dBm of broadband noise is generated along with the desired signal If the desired signal is 20 dBm and the result is measured on a power meter the reading will be about 0 5 dB high To accurately measure the sig
51. AVE LOCK CLEAR LOCK or ENTRY OFF SAVE in register n RECALL from register n ALTernate with register n I O read SHIFT KHz msec UNLK indicators SHIFT EXT Power LVL STEP size POWER LEVEL SWEEP TIME CW RESolution not used not used PWR SWEEP not used Power meter leveling IMETER Decoupled ATN ALC SHIFT PNR SWP Attenuator control SHIFT SLOPE Bypassed ALC SHIFT METER not used 10 CW frequency 11 CF center frequency 12 AF delta frequency 13 START frequency 14 STOP frequency 15 Marker 1 not used 16 Marker 2 17 Marker 3 1 channel SHIFT GHz dB m 18 Marker 4 1 O subchannel SHIFT MHz sec Marker 5 write SHIFT kHz msec Sweep time limit programming code TL not used Fault diagnostic SHIFT MANUAL 247 256 not used not used FREQuency STEP size Calibration constants accessed BYTE 3 shows the presently active and previously active markers The marker information is coded in bit groups 0 2 active marker 3 5 previously active marker and 6 7 not used the decimal value of those bit groups is the marker number For example BIT NUMBER 7 65 43 2 1 0 BIT PATTERN 1 001 1 is decoded as active marker is M3 decimal value of bits 0 2 is 3 and previously active marker is M2 decimal value of bits 3 5 is 2 BYTE 4 shows the on off status of the markers and m
52. BY that is delivered to the instrument through the line power module The module setting must match the locally available voltage and be fused to provide a measure of safety to the instrument and the operator To determine the module s voltage setting first measure the locally available ac power source The HP 8340B 41B requires either 100 120 200 or 240 volts with a tolerance of 10 The HP 8340B 41B also requires an ac frequency of 47 5 Hz to 66 Hz Some installations may need an autotransformer and or frequency converters to meet the voltage and frequency requirements After obtaining suitable voltage and ac frequency position the selector cam as shown in the accompanying illustration The proper fuse rating also corresponds to the voltage selection and these ratings are printed on the rear panel of the HP 8340B 41B adjacent to the line power module the fuses are also listed in Section Installation of this Manual i Appropriate power line cords are listed in Section Il Installation Figure 3 24 Power Line Module HP 8340B 41B Operating Information 3 51 HP IB Programming INTRODUCTION HP IB the Hewlett Packard Interface Bus is the instrument to instrument communication system between the HP 8340B 41B and up to 14 other instruments Any instrument having HP IB capability can be interfaced to the HP 8340B 41B including non HP instruments that have GPIB IEEE 488 ANSI MC1 1 or IEC 625 capability
53. C and Attenuator Diagnostic Functions Display M N and DISPLAY M N 20 30 Loop M N FREQ 20 30 SHIFT M1 SHM1 Frequencies FREQ Display Band and Y O Loop n yos DISPLAY VCO1 SHIFT M3 DISPLAY TEST SHIFT FREE RUN Display Unlock DISPLAY UNLOCK SHIFT EXT SHT3 3 11 Display Fault DISPLAY FAULT DISABLE BAND SHIFT MHz 2 3 Hz SHMZ23HZ CROSS SHIFT kHz 0 Hz SHKZOHZ RE ENABLE BAND SHIFT MHz 2 4 SHMZ22HZ CROSS SHIFT kHz 0 Hz SHKZOHZ Cause Manual MANUAL BAND SHIFT MHz 2 2 Hz SHMZz22HZ Band Cross CROSS SHIFT kHz 0 Hz SHKZOHZ Turn Off DIAGNOSTICS OFF SHIFT M5 SHMS5 Diagnostic Display SHIFT GHz dB m SHGZ Band Cross Control 3 16 SELECT CHANNEL Read Write to SELECT SUBCHANNEL SHIFT MHz sec 5 2 Internal Circuits WRITE DATA SHIFT kHz msec SHKZ READ DATA SHIFT Hz AUTO SHHZ 1 SHIFT M5 will not deactivate the Front Panel Display Test Instead press INSTR PRESET or cycle power off then on INSTR PRESET will restore the instrument to its standard starting condition Cycling the POWER switch will restore the instrument to its previous state HP 8340B 41B Operating Information 3 9 Table 3 1 Index by Mode and Function 6 of 7 HP IB Reference Code Figure HP iB Functions CLEAR BOTH STATUS BYTES OUTPUT BOTH STA
54. C connectors are listed in this Figure PANEL LAYOUT FREQUENCY STANDARD SWEEP 10MHz REF INT 51 EXT EXT TRIGGER 0 5V GHz OUTPUT OUTPUT ee eg AUTE PEN LIFT STOP SWP T 6 6 FUNCTIONS 0 5V GHz outputs a voltage that is proportional to the RF output frequency with a ratio of 0 5 volt output per 1 GHz RF frequency Load impedance should be 24 Accuracy is 0 5 V GHz 196 2 mV An output voltage ratio of 1 volts GHz to a maximum of 19V can be achieved by adding two jumpers on the A28 SYTM board see Section VIII SWEEP OUTPUT is provided by a rear panel BNC connector and an identical front panel BNC connector The output voltage range for this connector is 0 to 10 volts dc When the HP 8340B 41B is sweeping the SWEEP OUTPUT is 0 Vdc at the beginning of the sweep and 10 Vdc at the end of the sweep regardless of sweep width In CW mode the SWEEP OUTPUT ranges from 0 Vdc at the 10 MHz minimum frequency of the HP 8340B 41B to 10 Vdc at the 26 5 GHz maximum frequency 20 GHz with HP 8341B with a proportional voltage for frequencies between 10 MHz 26 5 GHz 20 GHz with HP 8341B Pressing CW then MANUAL locks the CW frequency but allows a full range voltage output from the SWEEP OUTPUT controlled by the rotary KNOB useful for example when scaling an X Y recorder The output impedance at this SWEEP OUTPUT connector is nominally 1 Figure 3 13 also describes SWEEP OUTPUT 10 MHz REF OUTP
55. EL LAYOUT NENNEN FUNCTION START STOP FREQ FREQ FREQ STEP Ca CW RES LVL STEP POWER LEVEL 200M EP SHIFT FUNCTIONS START FREQ HP IB FA selects the start frequency for start stop swept operation Press START FREQ then use either the rotary KNOB the STEP keys or the numerical keys with a terminator key to set the desired value The start frequency must be at least 100 Hz lower than the stop frequency If there is less than 100 Hz between start stop or if the start frequency is greater than the stop frequency the HP 8340B 41B will change the start or stop frequency to achieve the required separation The order in which start stop is entered is not important If start stop mode is inter changed with CF AF mode by pressing either of the start stop keys and then either of theCF AF keys the sweep limits are the same The start frequency appears in the left FREQUENCY MHz display SHIFT START FREQ HP IB SHFA scales the frequency displays by a multiplication factor of 30 to 30 This is used for example when a frequency doubler or tripler is connected to the RF output of the HP 8340B 41B and the display values are multiplied by a factor of two or three to indicate the system output frequency Press SHIFT START FREQ then enter the integer multi plication factor 30 to 30 followed by any terminator key The selected multiplication factor effects all frequency functions start stop
56. F which will cause OFF to appear in the POWER dBm display and will cause the output power to be turned off output lt 100 dBm Press RF again to turn on the RF output restoring the last entered power output SHIFT RF has the same effect on the HP 8340B 41B as SHIFT INT RF OUTPUT CONNECTOR The HP 8340B is equipped with a precision 3 5 male connector The HP 8341B uses a standard Type N female connector The output impedance SWR and other electrical characteristics are listed in the specification tables in Section When making connections carefully align the center conductor elements then rotate the knurled barrel while the mating component remains still Tighten until a firm contact is obtained CARE OF APC AND PRECISION 3 5 CONNECTORS HP 8340B only Considerable care must be used when working with APC 3 5 connectors Do not deform the connector by excessive tightening force and do not allow the connector to get corroded scratched or dirty If cleaning is necessary use a firm lintless brush only do not use any cleaning solvents since solvents can chemically damage the plastic bead that supports the center conductor If this connector is mechanically degraded in any way high frequency losses will occur Figure 3 17 RF Keys Output 3 of 3 83408 41B Operating Information 3 41 Rear Panel Connectors DESCRIPTION The electrical characteristics and requirements of the rear panel BN
57. FT MHz sec 3 10 SHKZ dt Write to IO SHIFT kHz msec 3 10 SHHZ Read from IO SHIFT Hz AUTO 3 10 SLmdt Power slope SLOPE 3 17 SMdt Sweep manual SNdt Steps maximum SP dt Set power step size STdt Sweep time SWEEP TIME 3 7 SVn Save instrument state SAVE 1 9 3 12 SW Swap network analyzer channels T1 Trigger free run FREE RUN 3 12 T2 Trigger line LINE 3 12 T3 Trigger external EXT 3 12 T1 b b Test HP IB interface TLdt Time line TS Take sweep UP Up step 3 8 The b Note The HP 8340B 41B automatically upshifts codes entered in lower case and ignores spaces placed between code groups The warning message HP IB SYNTAX ERROR appears in the ENTRY DISPLAY if an error is made in the programming format and the HP 8340B 41B will ignore the unrecognized code characters The HP 8340B 41B also clears HP IB DIO line 8 which sometimes is used as a parity bit HP IB lines are explained later in this Section lower case letters listed after the codes indicate typical suffix parameters as follows If no suffix follows a code in this Table the code represents either a self contained immediate execute function or one of the terminator codes that scale and define the associated numerical data indicates that alphanumeric ASCII characters are associated with this code indicates binary information consisting of 8 bit bytes Typically binary information is transmitte
58. HECK INSTR 1110 FUNCTIONS LOCAL HP IB LOCAL command The front panel keys except LOCAL and the POWER switch are inoperative when the HP 8340B 41B is being remotely controlled by a computer Press LOCAL to cancel computer control and to reactivate the front panel keys LOCAL does not work if the computer executed a LOCAL LOCKOUT command as explained in the HP IB section of this chapter SHIFT LOCAL no HP IB code causes the HP IB address to appear in the ENTRY DISPLAY The factory set address is 19 however any unique address between 00 30 can be assigned to the HP 8340B 41B by pressing SHIFT LOCAL entering the address numbers and pressing any termi nator key GHz MHz kHz Hz This new address remains in effect until again changed by the oper ator The calibration constants described in Section VIII can be configured to disable the SHIFT LOCAL function thus locking the HP 8340B 41B to the address specified in the calibration con stants SAVE HP IB SVn n 1 9 allows up to 9 different front panel settings to be stored in memory registers 1 through 9 Instrument settings can then be recalled via the RECALL n n 0 through 9 where 0 is the last used front panel setting function or a memory setting can be alternated with the current front panel setting with the ALT n n 1 9 function Set the front panel controls to any desired configuration then press SAVE which will cause SAVE
59. HP 8340B 41B Decimal Value SHIFT START FREQ SHIFT STOP FREQ SHIFT CF SHIFT AF SHIFT CW SHIFT POWER LEVEL SHIFT SWEEP TIME SHIFT SHIFT SHIFT GHz dB m SHIFT CONT SHIFT SINGLE SHIFT MANUAL SHIFT M1 SHIFT M2 SHIFT M3 SHIFT M4 SHIFT M5 SHIFT FREE RUN SHIFT LINE SHIFT EXT SHIFT MHz sec SHIFT kHz msec SHIFT Hz AUTO SHIFT INT SHIFT SHIFT XTAL SHIFT METER SHIFT AMTD MKR SHIFT PEAK not used SHIFT OFF SHIFT PWR SWP not used SHIFT SLOPE not used SHIFT LOCAL SHIFT RF SHIFT SAVE SHIFT 0 SHIFT RECALL SHIFT 1 SHIFT ALT SHIFT 2 not used SHIFT 3 SHIFT PULSE SHIFT 4 SHIFT 5 SHIFT AM SHIFT 6 SHIFT ENTRY OFF SHIFT 7 SHIFT SHIFT 8 SHIFT e SHIFT 9 not used not used 3 72 Operating Information 8340B 41B BYTE 2 shows the presently active function Decipher the decimal value of BYTE 2 as follows Active Function 4 Function HP IB address SHIFT LOCAL not used ZOOM frequency function MANUAL sweep Frequency offset SHIFT STOP FREQ Frequency multiplier SHIFT START FREQ RF SLOPE e non numerical function either S
60. IONS POWER dBm The available output power of the HP 8340B 41B is shown in this display rounded to the nearest 0 1 dB Depending on the installed attenuator the available power ranges from a minimum of 110 00 dBm to a maximum that depends on frequency with a resolution of 0 05 dB see Table 1 1 for the specified maximum power available for each frequency band If the user requests a power level that the HP 8340B 41B cannot provide the instrument will select the closest available power and show that value in the POWER dBm display to 0 1 dB in this situation the ENTRY DISPLAY which shows user selected power level will not match the POWER dBm display which shows actual power The procedures for setting the power level are explained in Figures 3 7 POWER LEVEL and 3 17 POWER SWEEP PEAKING and RF OFF This display can be blanked turned off by pressing SHIFT CONT Although the display is blank the power functions can be changed by the same local and remote procedures that are used with an active display Press SHIFT CONT to regain an active display INDICATORS UNLEVELED The red UNLEVELED annunciator indicates trouble either from operator error or machine malfunction with one exception Operator error request for too much power If the operator requests a power output that is too high for the HP 8340B 41B at that frequency the UNELEVELED annunciator lights Typically the HP 8340B 41B can deliver more power than li
61. PUT 719 130 END The can precede or follow the programming code for the function key that is EKCW and CWEK are functionally equivalent If EK is output by itself the KNOB will control the last activated function 80 OUTPUT 719 1062 FB14GZ PL 90DB ST100MS 90 OUTPUT 719 EK 100 END Line 80 establishes a start frequency of 10 GHz stop frequency of 14 GHz power level of 90 dBm and a sweep time of 100 milliseconds Line 90 enables the KNOB which will control the sweep time since that was the last activated function Using Keys that Toggle ON OFF Several keys such as the MODULATION keys activate functions that are either ON or OFF To turn a function ON or OFF add a 0 OFF or 1 ON suffix to the key s programming code For example 200 REM TURN THE AMTD ON 210 OUTPUT 719 AK1 220 PAUSE 230 REM TURN THE AMTD OFF 240 OUTPUT 719 Operator s Programming Check To check the various programming codes that duplicate front panel operations enter this BASIC program or equivalent 10 DIMA 60 20 719 30 PRINT ENTER PROGRAMMING CODES 40 INPUT A 50 OUTPUT 719 A 60 GOTO 30 70 END RUN the program and enter any combination of programming codes 60 characters maximum when prompted for example ENTER PROGRAMMING CODES FA12GZ FB18GZ PL 65DB STAU followed by RETURN or END LINE The HP 8340B 41B should imm
62. SHIFT MANUAL HP IB SHS3 activates the FAULT diagnostic routine When the amber FAULT annunciator appears in the ENTRY DISPLAY press SHIFT MANUAL to initiate the FAULT diag nostic which will cause FAULT CAL KICK ADC PEAK to appear in the ENTRY DISPLAY The flashing cursor indicates which circuit CALibration constants KICK pulses Analog to Digital Converter power PEAKing or TRacKing is causing the problem Refer to the In Case of Difficulty section FREE RUN HP IB 1 allows internal triggering of the any sweep function and is the fastest possible way to accomplish the sweep retrace cycle SHIFT FREE RUN HP IB SHT1 activates the display self test diagnostic function Press SHIFT FREE RUN which will cause every segment of every LED in the displays to light followed by a marching pattern of every character in the display lexicon Press INSTR PRESET or cycle the POWER switch to cancel this diagnostic routine INSTR PRESET will restore the instrument to its standard starting condition Cycling the POWER switch will restore the displays to their previous condition If this marching display ever appears spontaneously especially at power on the main processor circuit has failed and Section VIII Service should be consulted for further instructions Figure 3 11 Sweep and Trigger Keys 2 of 3 HP 8340B 41B Operating Information 3 29 LINE HP IB 2 triggers the sweep functions
63. Save Recall registers to Instr Preset cond itions Working cal ibration constants overwritten by protected cal constants Alternate Sweep Mode SHMZ18HZ SHKZOHZ SHIFT MHz 1 8 Hz SHIFT kHz 0 Hz Security Memory 3 12 Erase Power Level and Control POWER LEVEL POWER SWEEP ON POWER SWEEP OFF SLOPE ON SLOPE OFF RF ON RF OFF POWER LEVEL Power Sweep Mode PWR SWP SLOPE Power Slope Mode RF1 RFO RF Power Peak Output Power RP1 PEAK ON CW Mode or Manual Sweep PEAK OFF Instantaneous Peak FAST PEAKING Tracking AUTO TRACKING Calibration CALIBRATION INTERNAL EXTERNAL CRYSTAL EXTERNAL SHIFT AMTD MKR SHAK SHRP SHIFT PEAK INT A XTAL A2 POWER METER METER A3 Leveling Modes 3 16 DISABLE ALC TO CONTROL MODULATOR DRIVE SHIFT METER SHA3 DIRECTLY ENABLE EXTERNAL SOURCE MODULE LEVELING MODE SHIFT XTAL SHA2 iN 3 8 Operating Information HP 8340B 41B Table 3 1 Index by Mode and Function 5 of 7 18 Reference i K Function eys Code Figure Power Level and Control Cont d DECOUPLE ALC AND ATTENUATO CONTROLE er R SHIFT PWR SWP SHPS INDEPENDENTLY 347 CONTROL STEP ATTENUATOR SHIFT SLOPE SHSL or AT INDEPENDENTLY Independent Control of AL
64. TPUT A57P1 62 7 5 wn x Figure 3 21 HP 8410 Interface 2 of 2 3 48 Operating Information HP 8340B 41B HP 8755C Interface Cable DESCRIPTION The HP 8755C Scalar Network Analyzer is connected to the HP 8340B 41B at this connector Rear Panel Connector Interface Cable 8755C ALT SWP INTERFACE Connect the HP 8755C Scalar Network Analyzer to the HP 8340B 41B at this connector using Inter face Cable 8120 3174 to provide the alternate sweep function An Operating Guide at the end of Section explains the HP 8755C to HP 8340B 41B interconnections The pin configuration and electrical requirements for this connector are described in Section VIII Service of this Manual Figure 3 22 HP 8755C Interface Cable HP 8340B 41B Operating Information 3 49 Fan Assembly DESCRIPTION Maintenance of the filter element for the fan is described in this Figure Filter Element HP Part Number 08340 00018 The foam filter element requires regular inspection and cleaning The cooling fan for the HP 8340B 41B is powerful and pulls a large amount of air through its filter element subsequently the filter element collects dust smoke and other contaminants even from environments that seem quite clean To prevent impaired cooling from a dirt clogged filter it is imperative that the filter be inspected regularly and replaced as needed Filter replacement
65. TUS BYTES MASK STATUS BYTE 1 EN MASK STATUS BYTE 2 OUTPUT LEARN op STRING INPUT LEARN STRING OUTPUT MODE STRING OUTPUT ACTIVE OUTPUT NEXT BANDCROSS FREQUENCY OUTPUT COUPLED BE PARAMETERS OUTPUT DIAGNOSTICS OUTPUT FAULTS OUTPUT FIRMWARE ID OUTPUT LAST n LOCK FREQUENCY OUTPUT INTERROGATED PARAMETER OUTPUT POWER LEVEL Status Bytes and Service Requests Output Operating Configuring Output Parameters NETWORK ANALYZER CONFIGURE ADVANCE TO NEXT BANDCROSSING KEYBOARD RELEASE SWAP CHANNELS Network Analyzer Function 3 10 Operating Information HP 8340B 41B Table 3 1 Index by Mode and Function 7 of 7 HP IB Reference Code Figure HP IB Functions Cont d ENABLE EK HP 8340B 41B KNOB Control Knob ENABLE REMOTE KNOB STEPPED SWEEP INCREMENT IF FREQUENCY Sweep Functions RESET SWEEP RS TIME LIMIT EN SELECT FOREGROUND Alternate State Selection SELECT AS1 BACKGROUND FAST PHASELOCK Fast Phaselock SELECT y INDEPENDENT Attenuator Control CONTROL OF AT ATTENUATOR TEST HP IB DATA HP IB Test TRANSMISSION HP 8340B 41B Operating Information 3 11 3 12 Power dBm Display DESCRIPTION This display shows the actual power delivered to the RF OUTPUT port of the HP 8340B 41B and contains the UNLEVELED warning indicator PANEL LAYOUT UNLEVELED POWER dBm FUNCT
66. TX end text SO shift out EM end of medium EOT end of transmission SI shift in SUB substitute ENQ enquiry DLE data link escape ESC escape ACK acknowledge DC1 direct control 1 FS form separator BEL bell DC2 direct control 2 GS group separator BS backspace DC3 direct control 3 RS record separator HT horizontal tab DC4 direct control 4 US unit separator LF line feed NAK negative acknowledge DEL delete HP IB Abbreviations GTL goto local LLO local lockout LAO 30 listen address SDC selected device clear DCL device clear UNL unlisten PPC parallel poll configure PPU parallel poll unconfigure TAO 30 talk address GET group execute trigger SPE serial poll enable UNT untalk TCT take control SPD serial poll disable SCO 31 secondary command COMPUTER ACCESS OF HP IB LINES The I O Programming Guide for the specific computer being used must be consulted for detailed information about direct access to the HP IB lines however the intent of the following discussion is to introduce the fundamental procedures involved in this type of programming After this introduction the programmer will know what specific information to look for in the computer s I O Programming Guide HP 8340B 41B Operating Information 3 01 Sending HP IB Messages The BASIC statement used to transmit information directly to the HP IB lines is the SEND statement which has this syntax interface select code expression string expression numeric
67. UT provides a 0 dBm 10 MHz signal derived from the internal frequency standard of the HP 8340B 41B Test instruments are connected to this 50 Q BNC connector while the 10 MHz crystal oscillator is being adjusted as described in Section V Adjustments of this Manual or this can be the master clock reference output for a network of instruments Figure 3 18 Rear Panel BNC Connectors 1 of 2 3 42 Operating Information HP 8340B 41B INT EXT SWITCH amp CONNECTORS select either the internal INT 10 MHz crystal oscillator frequency standard or an external EXT frequency standard to be used as the master timebase for the HP 8340B 41B To select the internal standard place the switch in the INT position and connect a jumper cable between the INT and EXT BNC connectors the INT BNC is now outputting 10 MHz at 3 dBm To use an external standard disconnect the jumper change the switch to EXT and connect the external source to the EXT BNC connector The external source must be either 5 MHz 50 Hz or 10 MHz 100 Hz and provide 0 to 10 dBm into the 500 BNC connector When the switch is in the EXT position the amber EXT REF annunciator lights in the ENTRY DISPLAY EXT TRIGGER INPUT triggers the start of a sweep Trigger signal must be gt 2 volts 10 V maximum and wider than 0 5 usec Nominal input impedance is 2 Figure 3 11 describes the front panel procedures that are involved in sweep operations MUTE OUTPUT causes the se
68. X X X X X X X X x X X X X X x Xx x X X X gt lt X x x X gt lt x X Xx x x x x gt lt X x x x x x x x x x x x xxxxx A LA LA ch c ch och c ch c L L C L L L L Ch c LA L c l L 2 A L L L L L cA C C c C c c amp 2 2 o ooo lt Ao o mid 00O0oo0o0oooooooooooooooooooooooooooooozomiojuaa OO0O0O00O0 oOoOOoOOoOOoocoooo 0o0o0o0o0o0oooooooocooo oaaiuaa COOOOO OOo0OOo0Oo0o0O00 0 0o0o000o0o0o0 0oooooooozoo a a OOoOoo0 000022a 0O000222o00002 2 200002 2200002222000o0a2aaaco 00 0 0o 0O0 00 0o0 0o0 o0o0 o00 coco0 Do0 coo ococoooo oooo2oo 000 020 0000 0 0 0 0 0 0204 04040 0048 x 3 90 Operating Information HP 8340B 41B Table 3 3 The Standard ASCII Code of 3 HP iB DIO LINES 87654321 Decimal Hexadecimal u X1110101 v X1110110 w X1110111 x X1111000 y X1111001 z X1111010 X1111011 X1111100 1111101 X1111110 DEL X1111111 ASCI Abbreviations NUL null VT vertical tab SYN synchronous idle SOH start of heading FF form feed ETB transmission block STX start text CR carrige return CAN cancel E
69. a simple OUTPUT OS statement Reading HP IB Messages The HP IB lines are read by examining the computer s status registers using the STATUS statement The STATUS statement has this syntax interface register The function assignment of each status register is computer specific Figure 3 27 shows represen tative status register assignments from the HP 9826 and HP 85A computers HP 8340B 41B Operating Information 3 93 3 94 HP 9826 9836 926 936 Status Register 7 Most Significant Bit ATN DAV NDAC NRFD EOI True True True True True Value 2 048 Value 4 096 Value 8 192 Value 16 384 Value 32 768 Value 128 Value 64 Value 32 Value 16 Only if addressed to TALK else not valid Only if Active Controller else not valid SRQ True IFC REN True True Value Value 512 256 Least Significant Bit Value 1 024 HP 85A HP IB Status Registers Status Register Number SDC REN SRQ ATN DIO8 DIO7 0106 DIOS Figure 3 27 Operating Information Register Function Interface Identification Interrupt GET SCG Cause HP IB Control 64 Lines Not Applicable HP IB Data Lines HP IB Address 53 System Controller State Register Secondary Commands Representative Status Registers HP 8340B 41B Here is a BASIC example of reading the status registers 100 FORN 0TO6 110 STATUS 7 N S
70. aintain operating temperature and to the RAM circuits to maintain mem ory data in the ON position power is applied to the entire instrument When the HP 8340B 41B is connected to ac power for the first time or after a prolonged period without power the crystal oscillator s oven requires approximately 30 minutes to reach operating temperature the red OVEN annunciator in the ENTRY DISPLAY will be lighted during this warm up period Power must always be available to the HP 8340B 41B to keep the oven warm therefore when the instrument is not in use set the POWER switch to STANDBY and do not interrupt the ac power When the POWER switch is changed from STANDBY to ON the HP 8340B 41B will automatically initiate an internal circuit check then momentarily show the HP IB address in the ENTRY DISPLAY followed by setting the instrument functions to the last entered values If this sequence does not happen press INSTR PRESET to initiate an instrument check as described in Figure 3 12 If a warning annunciator lights at power on refer to the display Figures 3 3 3 4 3 5 and 3 6 for further instructions SWEEP OUTPUT is provided by a front panel BNC connector and an identical rear panel BNC connector The output voltage range for this connector is 0 to 10 volts dc When the HP 8340B 41B is sweeping the SWEEP OUTPUT is 0 Vdc at the beginning of the sweep and 10 Vdc at the end of the sweep regardless of sweep width In CW mode the SWEEP OUTPUT r
71. al INT 3 16 A2 Leveling external XTAL 3 16 A3 Leveling power meter METER 3 16 AK m Amplitude marker AMTD MKR 3 17 ALmn Alternate state ALT 3 12 AMm Amplitude modulation AM 3 14 3 15 AS Alternate state select AT d Attenuator AU Auto Hz Auto 3 10 BC Change frequency band CFdt Center frequency CF 3 7 CS Clear both status bytes CW frequency CW 3 7 DB dB m terminator GHz dB m 3 10 DFdt Delta frequency AF 3 7 DN Down step 3 8 DUm Display updating SHS1 EF Entry Display off ENTRY OFF 3 8 EK Enable rotary knob FAdt Start frequency START FREQ 3 7 FBdt Stop frequency STOP FREQ 3 7 FMm Frequency modulation FM 3 14 3 15 1 4 FM sensitivity d 1 or 10 3 14 3 15 FP Fast phaselock GZ GHz terminator GHz dB M 3 10 HZ Hz terminator Hz AUTO 3 10 IF Increment frequency IL 123b Input learn data IP Instrument preset INSTR PRESET 3 12 KR Keyboard release KZ kHz terminator kHz msec 3 10 MO Marker off MO OFF 3 9 Mi dt Marker 1 on M1 3 9 M2dt Marker 2 on M2 3 9 M3 dt Marker 3 on M3 3 9 M4 dt Marker 4 on M4 3 9 Mb5dt Marker 5 on M5 3 9 MC Marker to center frequency MRK CF 3 9 MD Marker delta MRKA 3 9 MO Marker off OFF 3 9 Marker sweep M1 M2 MKR SWEEP 3 9 MS milliseconds terminator kHz msec 3 10 MZ MHz terminator MHz sec 3 10 Network analyzer configure OA d Output active parameter OB d Output next band frequency OC 3d Ou
72. ales and Service office for information about retrofitting an HP 8340B 41B with one of these options Figure 3 19 Panel RF Outputs 3 44 Operating Information HP 8340B 41B HP IB Connector DESCRIPTION The procedures for connecting the HP 8340B 41B to other HP IB instruments is explained in this Figure 5 m Og omcor c Or Coo e o O The HP IB interface connector allows the HP 8340B 41B to be connected to any other instrument or device on the HP IB bus A complete illustration of pin configuration and signals on the HP IB inter face connector is given in Section II of this Manual i All HP IB instruments are interconnected with special HP IB cables and adapters These special cables shown in the accompanying illustration assure that the proper voltage levels and timing relations are maintained on the HP IB bus The adapters are principally extension devices for instru ments that have recessed or crowded HP IB connectors HP IB Interface Cables Available HP IB Cable Part Numbers 10833A 1m 33ft 10833B 2 6 6 ft 10833C 4m 13 2 ft 108330 O5m 1 6ft As many as 14 HP IB instruments can be connected to the HP 8340B 41B 15 total instruments in the system The cables can be interconnected in a star pattern one central instrument with HP IB cables emanating fro
73. anges from 0 Vdc at the 10 MHz minimum frequency of the HP 8340B 41B to 10 Vdc at the 26 5 GHz 7 55V at 20 GHz with HP 8341B maximum frequency with a proportional voltage for frequencies between 10 MHz 26 5 GHZ 20 GHz with HP 8341B Pressing CW then MANUAL locks the CW frequency but allows a full range voltage output from the SWEEP OUTPUT which is controlled by the rotary KNOB useful for example when scaling an X Y recorder The output impedance at this SWEEP OUTPUT connector is nominally 1 Figure 3 13 Power Switch Sweep Output 3 34 Operating Information HP 8340B 418 Modulation Keys DESCRIPTION These three keys select frequency modulation pulse modulation or amplitude modulation of the RF output These keys are used in conjunction with the front panel FM PULSE and AM BNC connectors shown in Figure 3 15 Table 1 1 lists instrument specifications for the three types of modulation PANEL LAYOUT MODULAT I ON ON OFF FUNCTIONS PULSE HP IB PM1 turns on pulse modulation PMO turns off the function activates the pulse modulation function When pulse modulation is in effect the RF output of the HP 8340B 41B is turned on full power selected and off 780 dB attenuation at a rate determined by the pulse modulation input described in Figure 3 15 Pulse and amplitude modulation can be in effect simultaneously amplitude modulation is described in a followi
74. ant however In unleveled mode the POWER dBm display accuracy is the complement of the corresponding leveled pulse accuracy that is 1 5 dB 70 3 dB for width 100 to 200 ns frequency 22 3 GHz If operating close to maximum ALC output there is some amplitude drift a few tenths of a dB due to component self heating when going from 10096 duty cycle to low duty cycles Since unleveled mode does not involve the integrate hold circuit there is no leakage induced ampli tude drift between pulses Consequently very long periods may be employed that are limited only by the long term drift of the modulator drive circuits This is not negligible and should be characterized by the user at the frequency of interest Drifts of a few dB should be expected during warmup Since this mode is not feedback leveled the power changes markedly with frequency In unleveled mode the ALC inputs control the linear modulator directly so the response time is not dependent on pulse parameters The response time is 70 us maximum in CW Sweeps gt 5 seconds normal AM or 4 us maximum for sweeps lt 5 seconds AM works in unleveled mode but the linearity and sensitivity varies with power level and frequency See the pertinent preceding section Input Characteristics When pulse mode is activated the HP 8340B 41B RF output is controlled by the voltage at the pulse input The input circuit is shown in Figure 3 36 The output is off for inputs below approximately 1 5V
75. any marker key to make that marker active After INSTR PRESET all markers are initialized to 13 255 GHz on the HP 8340B and 9 995 GHz on the HP 8341B otherwise the last used marker values will be remembered by the 8340B 41B for to three years even with disconnected ac power SHIFT M1 HP IB is a service diagnostic that shows from left to right the M divisor divisor M N frequency and 20 30 loop frequency Consult the In Case of Difficulty section for addi tional information SHIFT M2 HP IB SHM2 is a service diagnostic that shows from left to right the band number and the YIG oscillator YO frequency Consult the In Case of Difficulty section for additional informa tion SHIFT M3 HP IB SHM93 is a service diagnostic that shows from left to right the PLL 2 VCO frequency and the PLL 3 upconverter frequency Consult the In Case of Difficulty section for addi tional information Figure 3 9 Frequency Marker Keys 1 of 2 3 24 Operating Information HP 8340B 41B SHIFT MA SHM4 initiates a possible 18 diagnostic tests These tests are labeled 14 to 31 Other tests are initiated at power These tests are labeled 0 to 13 The results of all of these tests are indicated in the ENTRY DISPLAY as either a global PASS or FAIL Each of the test results may be viewed by entering the test number via the STEP keys NUMERICAL keys or KNOB The te
76. arker functions If a bit is set True 71 the marker or function is on if the bit is False they are off This is the bit code Bit Marker or Function MKR SWP M1 M2 M3 M4 M5 not used always 0 MRK A 8340B 41B Operating Information 3 73 BYTE 5 shows the status of the TRIGGER SWEEP and FREQUENCY modes Like byte 3 the mode information is organized by bit groups and is decoded by using the decimal value of those groups This is the bit group organization Bits Mode Information 0 1 TRIGGER MODE 0 FREE RUN 1 LINE 2 EXT 2 4 SWEEP MODE 0 CONT 1 SINGLE 2 MANUAL with Hz resolution code SM 3 not used 4 MANUAL with STEP resolution code SN 5 7 FREQUENCY MODE 0 START STOP 1 CF AF 2 CW with sweep on 3 CW with sweep off BYTE 6 shows the status of miscellaneous modes and functions which are ON if the appropriate bit is True 1 or are OFF if the bit is False Bit Mode or Function 0 AMTD MKR 1 not used always 1 2 not used always 1 3 not used always 0 4 Entry enabled and rotary KNOB on 5 SAVE lock enabled 6 ALT mode 7 Keyboard SHIFT on BYTE 7 shows the status of the power and leveling functions The decimal value of bit group 0 1 indicates the leveling modes while the remaining bits indicate whether the function is on 1 or off 70 Bit Mode or Function 0 1 ALC leveling modes 0 INT 1 XTAL 2 METER not
77. arting condition Cycling POWER switch will restore the instrument to its previous state Figure 3 3 Power dBm Display 2 of 2 3 14 Operating Information HP 8340B 41B START CW CF Frequency Display DESCRIPTION This display shows in megahertz either the start frequency the CW frequency or the CF center frequency of the HP 8340B 41B depending on its current operating mode PANEL LAYOUT C SW FREQUENCY MHz 0 00000 FUNCTIONS One of three frequencies is shown in this display Start CW or CF Figure 3 7 explains the imple mentation of these three functions This display can be blanked turned off by pressing SHIFT CONT Although the display is blanked the Start CW or CF values can be changed by the same local or remote procedures that are used when the display is active Press SHIFT CONT again to turn the display on INDICATORS START CW and CF These three amber annunciators indicate which function value is shown in the display DIAGNOSTICS Press and hold INSTR PRESET to light the three annunciators then release INSTR PRESET and press SHIFT FREE RUN which will light every LED segment 8888888888888 Press INSTR PRESET or cycle the POWER switch Figure 3 4 START CW CF Frequency Display HP 8340B 41B Operating Information 3 15 STOP AF Frequency Display DESCRIPTION This display shows in megahertz either the Stop frequency or the AF frequ
78. as intensified dots on a CRT display press AMTD MKR to change all of the markers to amplitude spikes Press AMTD MKR again to return to intensified dot markers SHIFT AMTD MRK HP IB SHAK causes an instantaneous execution of the peaking function when the HP 8340B 41B is in CW or manual mode This is one time implementation of peaking where the function is quickly turned on then turned off Peaking is explained in the next paragraph PEAK HP IB RP1 turns on peaking RPO turns off peaking aligns the output filter SYTM so that its passband is centered on the RF output in CW or manual sweep mode Peaking is used to obtain the maximum available power and spectral purity and best pulse envelopes at a given frequency Press PEAK and the HP 8340B 41B will automatically peak the present CW frequency and continue to peak new frequencies as they are entered by the KNOB or the STEP keys or the numerical keys with a terminator key If PEAK is on for an extended time the peaking function will automatically re peak every 7 minutes Press PEAK again to cancel this function When PEAK is activated the HP 8340B 41B performs a coarse alignment and then fine alignment that begins at the final setting of the coarse search SHIFT AMTD MKR initiates only a fine alignment which begins at the present instrument setting SHIFT AMTD MKR is faster but has less adjustment range than PEAK SHIFT PEAK described in the next
79. as a single sweep or an instantaneous measurement from all instruments or an individually addressed instrument If the HP 8340B 41B is in analog sweep mode TRIGGER starts the sweep if in CW manual sweep or fast phaselock code FP mode TRIGGER increments the frequency When the upper frequency limit is reached either the stop frequency for swept modes or maximum instrument operating frequency for CW mode the next TRIGGER com mand will initiate a retrace to the starting frequency The syntax is device TRIGGER selector A BASIC example 10 TRIGGER 7 to simultaneously trigger all HP IB instruments or 100 TRIGGER 719 to trigger an instrument at address 19 or 100 TRIGGER 719 721 712 to trigger instruments at addresses 19 21 and 12 Related statements used by some computers RESUME SEND The preceding statements are primarily management commands that do not incorporate instrument specific programming codes The following two statements do incorporate programming codes and are used for data communication 3 56 Operating Information HP 8340B 41B Output Output is used to send function commands and data commands from the controller to the addressed instrument The syntax is OUTPUT selector expression E line number expression where USING is a secondary command that formats the output in a particular way such as binary or ASCII representation of nu
80. but typically is within 1 5 dB at 2 usec width The detector s rise time depends its output resistance which drops with increasing temperature Therefore the narrow pulse leveling accuracy improves higher operating temperatures Narrow pulse accuracy is also power level dependent Very high ALC levels reduce the detector s output resistance improving rise time and therefore accuracy The r se time of alog amp is dependent on signal level degrading with small signals In low band 2 3 GHz the log amp is faster than the detector at any ALC level above 10 dBm so there is no degradation due to the log amp in any coupled mode operation In high band the log amp rise time at ALC 10 dBm is slow enough to be comparable to the detector rise time Therefore as power is decreased the leveling accuracy slightly degrades narrow pulse amplitude grows relative to CW The leveling specifications apply to coupled operation with no AM in other words ALC gt 10 dBm Using the decoupled mode or AM the ALC level can be driven down to 20 dBm or lower At 20 dBm the log amp slows down enough that high band accuracy is typically 1 5 dB at 150 nsec 3 0 dB at 100 nsec Decoupled mode can also be used to operate the ALC at high levels and achieve better narrow pulse accuracy The above discussion applies to internal leveling only Externally leveled pulse performance will of course depend on the detec
81. c functions are enabled by adding the SHIFT prefix to these keys PANEL LAYOUT SWEEP O TRIGGER FUNCTIONS CONT HP IB S1 allows continuous sweep retrace sweep retrace cycling of the HP 8340B 41B The sweep is initiated by one of the TRIGGER functions as explained later in this Figure while the sweep speed is controlled by the SWEEP TIME function as explained in Figure 3 7 SHIFT CONT HP IB SHS11 disables displays SHS10 re enables displays blanks turns off all diplays on the HP 8340B 41B Although the displays are blanked the functions that are normally shown in the displays can still be changed in the usual manner and the changed values will be shown when the displays are reactivated The displays are reactivated in one of two ways Press SHIFT CONT again to restore the displays SINGLE HP IB S2 allows single sweeps of the HP 8340B 41B Press SINGLE to start the sweep which will sweep at a rate determined by the SWEEP TIME function explained in Figure 3 7 If SINGLE is pressed in the middle of a single sweep the sweep will abruptly stop and the HP 8340B 41B will retrace back to the starting point SHIFT SINGLE has no effect on the HP 8340B 41B MANUAL HP IB S3 allows manual sweeps Press MANUAL then use the rotary KNOB to manually sweep between the start stop limits In manual mode the HP 8340B 41B will not automati cally retrace at the sweep end poin
82. ched and the UNLEVELED annunciator lights For best display accuracy and minimum noise the ALC level should be greater than 10 dBm This is achieved by using attenuation equal to the tens digit of output power Example output power 43 dBm use ATTN 40 dB ALC 3 dBm When sweeping while externally leveled the output power changes with frequency in order to level at a distant point The POWER dBm display tries to follow this change Due to its heavy filtering at fast sweep speeds the meter displays an average power level When using mixers or in other situations where reverse power may be encountered caution is necessary See the decoupled mode and unleveled mode sections above Reverse power into the HP 8340B 41B when externally leveled makes the POWER dBm display read incorrectly unwanted RF energy entering the external detector causes the loop to level at the wrong power level Bandwidth When externally leveled the leveling loop bandwith differs from what it is when internally leveled If AM is on or when sweeping with sweep time 5 seconds the nominal loop bandwidth is Internal 150 kHz External crystal 80 kHz with square law detector 40 kHz with linear detector External power meter 0 7 Hz The significance of loop bandwidth is that it generally equals AM bandwith and influences the fastest useable sweep speed The best way to set sweep time is to increase it until measured flatness no longer changes
83. d T Figure 3 26 HP IB Handshake Timing 2 of 2 System Control Lines IFC SRQ REN EO The remaining five lines coordinate communications between the HP IB LISTENERS TALKERS and CONTROLLERS The system control lines are used as follows ATN Attention signals Command Mode when low True or Data Mode when high False All devices must monitor ATN at all times and respond to it within 200 nanoseconds In Command Mode the controller is the only talker in the network while all other devices are listening for instructions When a high False ATN signifies Data Mode data may be transferred along the DIO lines The meaning of each data byte is device dependent and selected by the instrument designer IFC Interface Clear when low True abruptly terminates all HP IB communications activity All talkers and listeners are unaddressed and along with the controllers go to an inactive HP IB state the instruments local functions are not impaired All devices must monitor IFC at all times and respond to it within 100 psec SRQ Service Request line is set low True by any instrument that needs service from the control ler An SRQ could result for example when an instrument is ready to transmit data upon the completion of a measurement or from an error condition When the controller detects an SRQ it performs a serial poll of all devices to determine which requested service and why polling is explained in t
84. d by using either the computer s CHR function which converts a decimal number to a string of binary bytes such as 100 OUTPUT 719 code amp CHR Cdecimal where the amp concatenates the CHR function to the programming code and prevents an end of line terminator from being placed between the code and the data or for codes that require strings of binary data an image specifier can be used for example 100 OUTPUT 719 programming code 110 OUTPUT 719 USING B byte s The final semicolon in line 100 inhibits an end of line sequence from the computer an EOL must not separate code from data The in line 110 supresses EOL that might occur between data bytes or from a coincidental data bit pattern that mimics an EOL sequence and the indicates that the subsequent variables represent binary data Table 3 2 HP 8340B 41B Programming Codes 4 of 4 Jj indicates decimal data which is allowed in any of these data formats single digit d Integer decimal d d Real decimal d d d d Exponential decimal d d d m indicates a 1 or a 0 must follow the code letters where the 1 suffix is usually used to turn on the function and the 0 suffix turns off the function n isa single digit 1 9 for SV and 0 9 for RC which indicates the desired memory register t indicates that a terminator is required Typically the p
85. d not quite reach its pedestal before it begins to fall The result is a dc output from the S H that is smaller than it would be in CW The ALC circuits respond by raising the RF output until that voltage is what it should be This is the reason for poor leveling accuracy with narrow pulses As the pulses are made nar rower their amplitude grows Operating Information HP 8340B 41B The amount of accuracy degradation as the pulses are narrowed varies with frequency temperature and power level The variation with frequency and temperature is due to detector characteristics and RF envelope shape The detector has a finite rise time determined by its output resistance and shunt capacitance At some frequencies there is a slight amount of overshoot on the RF envelope which tends to charge the shunt capacity faster resulting in better narrow pulse leveling accuracy A much more pronounced effect is due to the use of a different detector for frequencies below 2 3 GHz The low band detector has a higher shunt capacity in order to make it function properly at low frequencies For operation below 400 MHz a large amount of additional capacity is switched in enabling detector operation down to 10 MHz Trace 3 in Figure 3 34 is representative of operation above 2 3 GHz where pulse accuracy is within 1 5 dB at 100 nsec From 0 4 to 2 3 GHz the slower rise time gives a 1 5 dB specification at 200 nsec width Operation below 0 4 GHz is not specified
86. dBm and increments in 2400 discrete 0 05 dB steps to an end value of 10 dBm SWm network analyzer channels is used in conjunction with alternate mode and causes the foreground and background instrument states to be transposed Foreground refers to the present operating configuration of the HP 8340B 41B as seen on the front panel displays and indicators while background is the configuration that is derived from one of the SAVE RECALL registers 1 9 When the HP 8340B 41B is alternating between the fore ground and background configurations only the foreground configuration shows on the front panel displays and indicators even when the instrument is operating under background condi tions Hence only the foreground configuration can be changed SW transposes foreground and background causing the background to show on the front panel where changes can be made Define the foreground configuration as state B at the moment that alternating operation begins At any time thereafter SWO causes state to be the front panel state while SW1 causes state B to be the front panel state SW does not change any of the values in the SAVE RECALL register from which the background was derived even if the background values are changed when alternate mode is initiated the values in the RECALL register are transferred into the background register after this transfer only the background register is involved in alternating operations
87. data This timing diagram illustrates the handshake process by indicating the actual waveforms of the DAV NRFD and NDAC lines The NRFD and NDAC signals each represent composite waveforms resulting from two or more listeners accepting the same data byte at slightly different times which is usually caused by variations in the transmission path length and individual instrument response rates Two cycles of the handshake sequence are shown The handshake process follows this typical list of events Source initializes DAV to high False data not valid Acceptors initialize NRFD to low True none are ready for data and set NDAC low True none have accepted the data Source checks for error condition both NRFD and NDAC high then places data byte on DIO lines Source delays to allow data to settle on DIO lines Acceptors have all indicated readiness to accept first data byte NRFD goes high When the data is settled and valid and the source has sensed NRFD high DAV is set low First acceptor sets NRFD low to indicate that it is no longer ready then accepts the data Other acceptors follow at their own rates First acceptor sets NDAC high to indicate that it has accepted the data NDAC remains low due to other acceptors driving NDAC low Last acceptor sets NDAC high to indicate that it has accepted the data all have now accepted and NDAC goes high Source having sensed that NDAC is high sets DAV high This indicates to
88. e BC following mid sweep updates until next GET Bit 1 set true 1 Enable keyboard hold off released by KR 3 66 Operating Information HP 8340B 41B Bit 2 set true 1 Disable HP IB SYNTAX ERROR annunciator that would otherwise appear in the ENTRY DISPLAY Bits 3 7 Not used Bit 0 is set true by decimal 1 bit 1 is set by decimal 2 and bit 2 is set by decimal 4 A BASIC example that sets bits 0 1 and 2 true 100 OUTPUT 719 NA amp CHR C7 In this example the binary value of decimal 7 CHR 7 is concatenated to the NA code amp Alternatively a formatted OUTPUT statement could be used to output the same binary informa tion 100 OUTPUT 719 USING 2 7 The image specifier 2 indicates that two literal characters will be output followed by a single binary byte Consult the Operating Guide for the specific network analyzer being used for detailed interfacing information OA d Output Active parameter allows the computer to read the numerical value of the presently active HP 8340B 41B function The active function is the last used function and appears in an unblanked ENTRY DISPLAY A BASIC example 100 OUTPUT 719 5 2 FB75MZ PL10DB ST1SC 110 OUTPUT 719 120 ENTER 719 130 PRINT ACTIVE PARAMETER A Sweep time is the active parameter because it was the last entered function line 100 The OA value read by the computer read in line 120
89. e fastest possible frequency transition is necessary between CW frequencies FP can be used for fast transitions between steps in a stepped CW sweep or it can be used when the CW frequencies must be rapidly changed to any value in the frequency span of the HP 8340B 41B FP achieves rapid frequency transition by limiting some of the normal HP 8340B 41B fea tures The plotter control functions are disabled the 0 10 volt sweep ramp is frozen and the HP 8340B 41B does not wait for a complete locking of the phase lock loop oscillators before releas ing the HP IB handshake The FP code must have a numerical suffix 14 characters maximum in Hz units without any terminator code ASCII LF normally sent by the computer is the only allowable terminator that sets the starting frequency A BASIC example of a stepped CW sweep 100 OUTPUT 719 IP SF1KZ 110 OUTPUT 719 FP1E9 120 FOR J 1 0 100 130 TRIGGER 719 140 NEXT J 150 GOTO 110 Line 100 sets the step size SF to 1 kHz and causes the HP 8340B 41B to enter CW mode the unspecified CW frequency at this point will be the last used CW frequency or the IP default value Line 110 initiates fast phaselock mode and establishes a starting CW frequency of 1E9 Hz 1 109 Hz or 1 GHz At this point in the program the HP 8340B 41B is outputting 1 GHz CW but will not increment until line 130 is reached Line 150 causes a retrace to 1 GHz HP 8340B 41B Operating Information 3
90. e integrate hold switch is continu ously closed so the system responds in 70 us regardless of width or period Simultaneous AM and pulse modulation is provided by the HP 8340B 41B The AM is dc coupled and linear just as with normal CW leveling If AM is used to exercise the ALC below 10 dBm the narrow pulse leveling accuracy degrades as explained above The bandwidth is given by the equation 3dB BW 0 35 Tr where Tr is the resposne time to a step change described above Uneleveled Mode Used With Pulse Modulation Decoupled operation may be used for dynamic range extension or any of the other uses described for CW or AM Several pulse related problems may be treated with the unleveled SHIFT METER operating mode already described Narrow pulse leveling accuracy problems may be treated by simply not attempting to level them The unleveled mode allows the user to control the linear modulator directly The setting of this modulator does not change with pulse width so the pulse amplitude remains constant as the pulse is narrowed Pulses as narrow as 25 nsec may be produced in this mode To set the amplitude go to CW operation pulse off and set the desired power via the POWER dBm display As the pulses are narrowed the POWER dBm reading drops since it is measuring the output of the detector S H system and it is the limitations of this system which cause the narrow pulse leveling problems The real amplitude remains essentially const
91. e modulation mode which provides approximately 2us rise and fall times Press SHIFT PULSE to enter this mode The scalar analyzer s modulation output is connected to the HP 8340B 41B PULSE input The slow waveform reduces the spectral width of the output improving measurements made on filters with steep skirts This mode may be used for other purposes and functions properly for pulse widths wider than about 7us FURTHER INFORMATION This completes Section Ill of the HP 8340B 41B Synthesized Sweepers Operating and Service Man ual For further information there are several Programming Notes Operating Guides and general reference Application Notes that are applicable to the HP 8340B 41B Operating Information HP 8340B 41B
92. ector Characteristics As shown in Figure 3 33 crystal detectors may be characterized by three operating regions In the square law region Pin lt 20 dBm the output voltage is proportional to the square of the input voltage in other words proportional to input power In the linear region Pin gt 5 dBm the output voltage is directly proportional to the input voltage Because of this when leveling in the linear region 1 dB reference change causes a 1 dB power change while in square law a 1 dB reference change causes a 1 2 dB power change This should be understood when using power sweep or AM The power sweep function will sweep the reference by up to 40 dB but if a square law detector is being used the power will only sweep 20 dB The power sweep will only be linear if the operation is entirely in square law or entirely in linear In the transition region the power sweep will be non linear As may be seen in Figure 3 33 by drawing a line between 10 dBV and 50 dBV the worst deviation from a straight line is 3 dB of reference voltage or 2 dB of RF power The amplitude modulation system is designed to be linear with a square law detector With a linear detector the modulation depth will be more than expected and there will be significant distortion HP power meters have a rear panel output recorder output which responds linearly with power The output is 1 00V for full scale on whatever range is selected 50V for 3 dB below ful
93. ed by any terminator key The offset effects all frequency values start stop CF CW and markers but the offset cancels in difference functions such as AF A MRK and the dB GHz SLOPE function The offset value is not stored in the SAVE RECALL registers but the current offset value does change the values of a recalled register Cancel the offset by pressing INSTR PRESET or by entering an offset value of 0 CF HP IB CF selects the center frequency for center frequency delta frequency swept opera tion Press CF then use either the rotary KNOB the STEP keys or the numerical keys with a terminator key to set the desired value The order in which CF AF are entered is not important Start stop and CF AF modes can be interchanged without changing the actual sweep limits as described in the START FREQ paragraph The CF value appears in the left FREQUENCY MHz display SHIFT CF HP IB SHCF selects the incremental step size for the STEP keys the FREQ STEP function The step size can be as small as 1 Hz or as large as 10 GHz Press SHIFT CF then use either the numerical keys with a terminator key the rotary KNOB or the STEP keys which step in a 1 2 5 sequence at this time to set the desired increment After setting the step size appears in the right corner of the ENTRY DISPLAY An alternative procedure couples the FREQ STEP incre ment size to the AF frequency span Press SHIFT CF AUTO causin
94. ed signal versus a possible 15 dBm undesired one This 17 dB difference results in a maximum 0 1 dB shift in the HP 8340B 41B output level Reverse power is a problem with spectrum analyzers that do not have preselection capabability Some analyzers have as much as 5 dBm LO feedthrough coming out of their RF input at some frequencies The effects of reverse power are less in the heterodyne band 01 to 2 3 GHz where the power amplifier provides some broadband matching Similarly from 2 3 to 26 5 GHz reverse power that is within 10 MHz of the HP 8340B 41B s frequency may be partially absorbed by the YIG filter If the frequency difference is small enough to be within the leveling loop bandwidth typically 10 kHz CW 200 kHz sweep or AM the effect of reverse power is amplitude modulation of the HP 8340B 41B s output The AM rate equals the difference in RF frequencies Reverse power problems may be treated by using the unleveled mode as described below 3 100 Operating Information 8340B 41B A COUPLED MODE WITH 8 dBm OUTPUT 83408 418 ALC LEVEL RF OUTPUT 8dBm BdBm MIXER RF LEVEL ATTENUATOR SL LO CONTROL OdB 5 LO FEED LO LEVEL THROUGH IF 10dBm DETECTOR DETECTOR 5dBm MEASURES i MEASURES 5dBm ALC LEVEL REVERSE POWER B DECOUPLED MODE WITH 8dBm OUTPUT A HP 8340B 41B RLC LEVEL 2dBm RF OUTPUT MIXER 8dBm RF LEVEL ATTENU
95. ediately respond to your commands with in this example a 12 GHz start frequency 18 GHz stop frequency power level of 65 dBm and a sweep time set to auto auto selects the fastest possible sweep rate for a given frequency span The preceding applications of the OUTPUT command are sufficient for writing computer programs that duplicate all front panel operations The next subsection explains programming codes that do not have an equivalent key on the front panel HP 8340B 41B Operating Information 3 63 3 64 Unique HP IB Programming Codes Several programming codes are available which do not have an equivalent front panel key these codes are listed in Table 3 2 and described here in alphabetical order the lower case letters that follow each code mnemonic are explained in Table 3 2 ASm Alternate State Select is primarily used when the HP 8340B 41B is operating in certain network analyzer systems AS is always used in conjunction with alternate state mode ALT Figure 3 12 where it causes an abrupt change from one operational state to the other Use AS when automatic alternation does not occur for example when CW mode is used for one or both operational states or when it might be necessary to interrupt the alternating operation First establish alternating operation between the present operating configuration called the foreground state and one of the previously SAVEd operating configurations called t
96. elected by following the FM1 sequence with either 1 MHz or 1 0 Mhz respecitvely SHIFT FM has no effect on the HP 8340B 41B Figure 3 14 Modulation Keys HP 8340B 41B Operating Information 3 35 Modulation Inputs DESCRIPTION The external FM pulse or amplitude modulation signals are applied to the HP 8340B 41B at these three connectors PANEL LAYOUT MODULATION INPUT FUNCTIONS PULSE MODULATION INPUT is TTL compatible a TTL high input gt 2 volts causes maximum selected RF power output while a TTL low input causes minimum RF output gt 80 dB RF on off ratio The pulse repetition frequency is dc to 20 MHz in non leveled applications 100 Hz to 5MHz when internally leveled The specifications given in Section I detail the electrical requirements of the PULSE modulation input and explain the subsequent effects on the RF output The damage levels for this input are 2 12 volts or lt 20 volts This input is also used for the SHIFT PULSE operation AM MODULATION INPUT accepts a 1 volt to 1 volt signal at a frequency of dc to 100 Khz 3 dB bandwidth With an AM input of 0 volts the RF output level the reference level is unaffected at 1 volts input the RF is shut off and at 1 volts input the RF output is 100 6 dB higher than the reference level hence there must be 26 dB of headroom between the reference power level and the maximum power level available at that frequency The on 0
97. en when unleveled The AM input is DC coupled and a DC input will change the output power This change does not appear in the ENTRY DISPLAY but the POWER dBm display accurately indicates the real output When the instrument is internally leveled the UNLEVELED annunciator is off and AM is off the POWER display simply repeats the value shown in the ENTRY DISPLAY When externally lev P eled or the UNLEVELED annunciator is on or AM is on the POWER dBm display indicates the ALC 9 level and reflects the true output power This might not agree with the ENTRY DISPLAY value which shows the desired level in the absence of modulation HP 8340B 41B Operating Information 3 99 The above should be understood when using power sweep When the POWER dBm display is repeat ing the ENTRY DISPLAY it indicates start power If the POWER dBm display is indicating ALC level it shows the average power over the sweep The circuit is heavily filtered above 5 Hz Since the start and stop dwell times are unequal this averge reading has little meaning In a variety of situations it is possible to drive the ALC level below 20 dBm such as putting DC into the AM input or when externally leveled Since the internal detector is inaccurate at these levels the POWER dBm display would be very misleading For that reason and as a warning the POWER dBm display blanks at ALC levels below 22 0 dBm This may occur at an output power of 22 dBm 3
98. ency span of the HP 8340B 41B PANEL LAYOUT STOP AF FREQUENCY MHz ag OOO 000000 FUNCTIONS One of two frequencies is shown in this display Stop or AF Figure 3 7 explains the implementation of these two functions This display can be blanked turned off by pressing SHIFT CONT Although the display is blanked the Stop or AF values can be changed by the same local and remote procedures that are used when the display is active Press SHIFT CONT again to turn the display on INDICATORS STOP AF These two amber annunciators indicate which function value is shown in the display DIAGNOSTICS Press and hold INSTR PRESET to light the two annunciators then release INSTR PRESET and press SHIFT FREE RUN which will light every LED segment 8888888888888 Press INSTR PRESET or cycle the POWER switch to end this diagnostic routine This diagnostic also tests the three other displays NOTE INSTR PRESET will restore the instrument to its standard starting condition Cycling the POWER switch will restore the instrument to its previous state Figure 3 5 Stop AF Frequency Display 3 16 Operating Information HP 8340 418 Entry Display DESCRIPTION This display shows the active function and its present value and contains the OVERMOD REMOTE SRQ FAULT OVEN EXT REF and UNLK indicators PANEL LAYOUT OVERMOD REMOTE 580 FAULT EXT REF UNLK ENTRY DISPLAY HF B RDR5
99. eset by changing the calibration constants as described in Section VIII 3 Sweep time to AUTO 44 15 msec 33 32 msec on HP 8341B 4 CONT sweep FREE RUN trigger 5 All markers set to 13 255 GHz on the HP 8340B and 9 995 GHz on the HP 8341B center frequency of the sweep f 6 The checksum of the calibration data is calculated and if an error is detected then the calibration data in protected memory is used If the checksum of the protected data is not correct then default values are used and the FAULT annunciator lights in the ENTRY DISPLAY to indicate a calibra tion constant error press SHIFT MANUAL when the FAULT annunciator lights as described in Figure 3 11 7 All function values stored in memory registers 1 9 remain in their previous states 8 self test is performed and check LEDs are lighted Press INSTR PRESET at any time to test the instrument and restore the standard starting condition If either of the two red LEDs that are adjacent to INSTR PRESET labeled INSTR CHECK 1 II remain lighted after a preset the HP 8340B 41B failed the self test refer to Section VIII Service for further instructions SHIFT INSTR PRESET disables the SHIFT ALT function This command sets the default fre quency display multiplication factor to 1 and presets the instrument Figure 3 12 Instrument State Keys 2 of 3 3 32 Operating Information HP 8340B 41B SECURITY MEMORY ERASE i
100. et Marker Frequency Turn Off a Frequency Marker Turn On And Set Mkr A Turn Off Mkr A Turn Off Mkr A M5 OFF M5M0 3 9 Marker Marker 1 2 Sweep MKR SWEEP OFF meo Turn Off All Markers ALL OFF SHIFT OFF SHMO MKR OFF Marker 1 to Start M1 gt START Marker 2 to Stop M2 STOP SHIFT MKR SWEEP SHMP MKR A Marker Active Marker To MKR CF MKR CF MC Center Frequency Amplitude 9 AMTD MKR 1 AMPTD MKR OFF HP 8340B 41B Operating Information 3 5 Frequency Markers 3 17 Table 3 1 Index by Mode and Function 2 of 7 HP IB Reference Code Figure Sweep Mode Trigger and Time CONTINUOUS CONT Sweep Mode MANUAL FREQUENCY MANUAL S3 or SM SWEEP 9 11 FREE RUN FREE RUN Sweep Trigger LINE LINE EXTERNAL EXT RF Dwell Return Pre sweep Pre CW step delay time to 400 5 dwell ti SHMZ 17 H Increases dwel ime SHIFT MHz N I7 Hz SHKz Hz entered for value SHIFT kHz n Hz where where value up to 12 8 ms value Instrument Preset INSTR PRESET Modulation AM1 AMO Time Pulse SHIFT PULSE SHPM NORMAL PULSE MOD ON m PULSE MOD OFF FM SENSITIVITY 3 14 FM SENSITIVITY Disable ALC SHRF Search for Desired SHIFT INT or 3 16 Power Level SHAI Amplitude Modulation
101. g AUTO to appear in the ENTRY DISPLAY and the increment size will become 1 10 of the frequency span AUTO is the default condition after an INSTR PRESET The step size established by the FREQ STEP function is the same for start stop frequencies CF AF frequencies the markers and manual sweeps The STEP keys are explained in Figure 3 8 AF HP IB DF selects the delta frequency frequency span for center frequency delta frequency swept operation Press AF then use either the STEP keys the numerical keys with a terminator key or the rotary KNOB to set the desired value The HP 8340B 41B will sweep from 1 AF below to Ya AF above the center frequency The restrictions that apply to CF also apply to AF The right FREQUENCY MHz displays shows the AF value SHIFT AF has no effect on the HP 8340B 41B CW HP IB CW selects a synthesized CW frequency Press CW then use either the rotary KNOB the STEP keys or the numerical keys with a terminator key to set the desired value The right side of the ENTRY DISPLAY shows either AUTO if the STEP keys and KNOB are coupled to the AF frequency span or if they are not coupled see the SHIFT CF and SHIFT CW paragraphs for an explanation The left FREQUENCY MHz display shows the CW value SHIFT CW HP IB SHCW sets the sensitivity of the rotary KNOB the CW RES function for adjusting the CW value Press CW to enter CW mode and
102. h Option 003 Low Harmonics has a different maximum sweep rate Refer to the Option 003 supplement for the actual value TL sets a limit on the minimum sweep time with that limit ranging from 10 milliseconds to 40 seconds For example 100 OUTPUT 719 TL15SC changes the permissible sweep time range to 15 200 seconds STAU is normally used to obtain the fastest possible sweep time for a given frequency span however AU will not override a TL restriction TS Take Sweep initiates a single non interruptible sweep All HP IB commands are deferred until that sweep has been completed If TS is output while a sweep is in progress that sweep will abruptly stop retrace and begin a new non interruptible sweep The HP 8340B 41B will resume the previous sweep operations at the completion of the TS initiated sweep A BASIC example 100 OUTPUT 719 IP 56 110 PRINT PRESS CONTINUE TO START THE SWEEP 120 PAUSE 130 OQUPUT 719 TS 140 GOTO 120 This completes the listing of unique HP IB programming codes HP 8340B 41B Operating Information 3 81 SYSTEM TIMING Itis sometimes necessary to determine the time required for a sequence of programming codes to be implemented by the HP 8340B 41B This can be accomplished by the computer s set time and read time commands 100 set time command Ccomputer specific 200 OUTPUT 719 programming codes 300 read time command computer specific 310 PRINT TIME REGUIRED C
103. hat This is not long enough to cause overcorrections but speeds response time for 100 ns pulses by a factor of 100 During the period between pulses the integrate hold circuit is expected to hold the modulator drive constant Because of leakage currents the output will in fact drift causing the pulse amplitude to be in error This error will grow with off time and also temperature as leakage is strongly temperature dependent The circuit is designed worst case for 0 1 dB droop in 10 msec at an ambient tem perature of 55 C At 25 C a typical unit drifts about 1 dB per minute The drift may be in either direction HP 8340B 41B Operating Information 3 113 Response Time The response time to a step change in level is a function of pulse width and rate and is detailed in the specifications The response time is a function of ALC loop bandwidth which varies with frequency and power as explained in the AM section The listed response characteristics apply at the minimum expected loop bandwidth An intuitive feeling for response may be gained by the following At mini mum bandwidth in CW ittakes 70 us to respond to a change and settle to within 1096 of the size of the change In pulse mode the same degree of settling requires 70 us of closure of the integrate hold Switch This may come from one of 70 us pulse two 35 us pulses etc Any pulse less than 10 5 wide is treated as a 10 us pulse If the pulse period is less than 10 us th
104. he ground state For example code AL13 activates alternating operation between the foreground and background states with the background state being derived from the contents of memory register 3 the code parameters are ALnx where n 1 0 to activate deactive alternating opera tion and x 1 9 indicates the memory register that will be transferred to the background register With alternating mode in effect AS is used to abrubptly change the operating state 50 causes the present HP 8340B 41B operation whether that operation is foreground or background to abruptly halt retrace to the beginning of the foreground state and begin operating under the foreground configuration AS1 causes the present operation to abruptly halt retrace to the begin ning of the background state and begin operating under the background configuration After the AS initiated foreground or background change has been completed the previously established alternating state operation resumes A BASIC example 100 REM PREPARE BACKGROUND STATE SAVE IN REGISTER 3 110 OUTPUT 719 Cprogramming codes SV3 120 REM 130 REM PREPARE FOREGROUND STATE AND ALTERNATE 140 OUTPUT 719 Cprogramming codes AL13 150 REM 160 REM ABRUPTLY CHANGE STATUS IF NECESSARY 170 IF X Y THEN OUTPUT 719 51 180 IF X lt Y THEN OUTPUT 719 50 X and Y in lines 170 and 180 are arbitrary variables for a hypothetical test ATd Attentuator allo
105. he System Commands The controller can mask the SRQ to prevent any inconve nient interruptions as explained in the RE RM programming codes The HP 8340B 41B lights a red SRQ annunciator in the ENTRY DISPLAY when it initiates an SRQ REN Remote Enable when low True enables HP IB instruments to respond to commands from the controller or other talkers when high False all devices return to local operation The HP 8340B 41B lights an amber REMOTE annunciator in the ENTRY DISPLAY when REN is true and _disables front panel control of the instrument with three exceptions the POWER switch can only be controlled locally the LOCAL key re enables front panel control unless locked out by the controller and the rotary KNOB can be re enabled by an EK command from the controller All devices msut constantly monitor REN and respond to it within 100 psec HP 8340B 41B Operating Information 3 85 EOI End or Identify is used in conjunction with ATN When ATN is high False EOI goes low True to indicate the end of a data transmission sequence when ATN is low True and EOI is low True a parallel poll of the HP IB instruments is performed the HP 8340B 41B does not respond to parallel polling Typically HP IB data messages are sent as ASCII characters and are terminated with an ASCII LF line feed decimal 10 However when blocks of binary information are being sent LF cannot safely be used as a terminator because the LF bit pa
106. hen the RF output is coincident with a marker frequency intensity markers only as explained in Figure 3 9 STOP SWP IN OUT abruptly stops a sweep when this input is grounded Retrace does not occur and the sweep will resume when this input is ungrounded The open circuit voltage at this connector is TTL High and is internally pulled low when the HP 8340B 41B stops its sweep Externally forcing this input High will neither cause damage nor disrupt normal HP 8340B 41B operation Figure 3 18 Rear Panel BNC Connectors 2 of 2 HP 8340B 41B Operating Information 3 43 Rear Panel RF Outputs DESCRIPTION The two rear panel RF Output connectors one standard one an option are described in this Figure PANEL LAYOUT AUX OUTPUT RF OUTPUT 2 3 TGHz FUNCTIONS _ AUX OUTPUT 2 3 7 GHz is a type female connector that provides a 0 dBm Output from the HP 8340B 41B s fundamental YIG oscillator the higher frequencies obtainable from the HP 8340B 41B are multiples of this oscillator Impedance of this connector is 50 Q nominal RF OUTPUT is an optional rear panel RF output connector that is functionally equivalent to the standard front panel RF output connector which is described in Figure 3 17 Option 004 is a rear panel RF output with attenuator and Option 005 HP 8340B only is a rear panel RF output without attenuator The specifications for each option are listed in Section of this Manual Contact the nearest HP S
107. ility to another instrument accomplished by ASCII HT decimal 9 UNL Unlisten clears bus of all listeners in preparation for assigning new listeners accomplished by ASCII decimal 63 UNT Untalk unaddresses the current talker so that no talker remains on the bus accomplished by ASCII __ underscore decimal 95 These are the 12 bus messages refer also to the HP IB Command Statements that have the same names as these messages DATA represents the actual transfer of numerical information between instruments The pre vious BASIC examples used OUTPUT and ENTER for data messages the HP IB bus sequence for a typical OUTPUT statement is ATN MTA UNL LAG ATN ASCIIdata CR LF The HP IB sequence for a typical ENTER statement ATN UNL MLA TAG ATN ASCII data CR LF TRIGGER causes the listening instruments to perform in instrument defined function such as starting a sweep A typical HP IB sequence ATN UNL LAG GET REN line must be True before executing GET CLEAR causes the listening instruments to establish an instrument specific predefined state i The HP IB sequence ATN DCL forall bus instruments ATN UNL LAD SDC foran addressed instrument HP 8340B 41B Operating Information 3 87 3 88 LOCAL LOCAL LOCKOUT CLEAR LOCKOUT LOCAL REQUIRE SERVICE STATUS BYTE STATUS BIT PASS CONTROL ABORT causes listening instruments to switch from local front panel control
108. information cards located below the HP 8340B 41B Figure 3 7 Function Keys 3 of 3 HP 8340B 41B Operating Information 3 21 KNOB STEP Entry DESCRIPTION The rotary KNOB and STEP keys affect the function that is presently being shown in the ENTRY DISPLAY ENTRY OFF blanks the ENTRY DISPLAY PANEL LAYOUT ENTRY NENNEN res O gt 9 FUNCTIONS ENTRY OFF HP IB EF blanks turns off the ENTRY DISPLAY and disables the STEP keys and the rotary KNOB When any function key is pressed ENTRY DISPLAY is reactivated the ON indicator next to ENTRY OFF lights and the KNOB and STEP keys are enabled To blank the ENTRY DISPLAY without disabling the KNOB or STEP keys press SHIFT CONT as described in Figure 3 6 SHIFT ENTRY OFF HP IB SHEF recalls the Calibration Constant Access Function This com mand is used when one wishes to re enter the calibration constant mode after just exiting it This saves the trouble of entering the long Cal Constant key sequence again ROTARY KNOB HP IB EK allows analog type adjustment of the function shown in the ENTRY DISPLAY Press any function key to activate that function then turn the rotary KNOB to obtain the desired value SHIFT CW in figure 3 7 explains the procedure for adjusting the sensitivity of the rotary Knob Although the KNOB has the feel of an analog control it is actually a digital control that generates 120 pul
109. ion As long as the modulation depth remains constant across the frequency band use moderate rates and depths this system will level the power while providing amplitude modulation EXTERNAL SOURCE MODULE LEVELING The HP 8340B 41B provides an external leveling mode for use with compatible Hewlett Packard instruments which provides leveling at a remote location along with power calibration and flatness compensation Compatible instruments are the HP 83550 series millimeter wave source modules when driven by an HP 8349B Microwave Amplifier The HP 8349B may also be used in a stand alone amplifier configuration Refer to an appropriate HP 83550 mm wave source system guide for inter connect instructions Once the HP 8340B 41B HP 8349B HP83550 series instruments are hooked up press SHIFT XTAL on the HP 8340B 41B This causes EXT MODULE POWER XX XX dBm to be displayed in the ENTRY DISPLAY which will accept power level changes via the KNOB STEP keys or ENTRY keyboard The HP 8340B 41B will accept power level requests from 20 to 20 dBm however this range exceeds the operational range of existing mm wave source modules Refer to the mm wave source module manual for more information The SHIFT XTAL mode is unlike external leveling in that the POWER dBm display indicates the output power of the remote module not the HP 8340B 41B RF output This mode provides all the modulation features of an internally leveled HP 8340B 41B
110. l enhancement provisions These provisions are mentioned in the relevant parts of the local operation and HP IB programming subsections but a collective detailed explanation is made at the end of this Operation section Hewlett Packard periodically updates the operating information for the HP 8340B 41B in the form of a Manual Changes Supplement and publishes a series of Operating Guides and Programming Notes Contact the nearest HP Sales and Service office listed inside of the back cover of Volume 3 to obtain this supplemental information as it becomes available HP 8340B 41B Operating Information 3 3 Figure 3 11 Figure 3 9 Figure 3 8 Figure 3 6 Figure 3 3 Figure 3 4 Figure 3 5 Figure 3 7 Figure 3 10 T UNLEVELED START STOP py FREQUENCY MHz ode FREQUENCY MHz EMEN B340B 5 NTHES ZED SWEEPER 10MHz 26 5GHz HEWLETT PACKARD G oven ext SRO FAULT ENTAY DISPLAY ENTRY EEEENHENEEENE FUNCTION Se ENTRY a m Mel 7 8 3 ms essel s EEEE FREQUENCY MARKER MET RES ti STEP gt ww 9 2 ow nes D STATE MODULAT LON 100 9 amp u Ea SHIFT 0 BACK lt rua JJ 10 aaa tu ex cu a UC SPACE B parr uo IL
111. l scale 10V for 10 dB below full scale These numbers may be seen directly on the 0 1 WATTS scale on an analog power meter e g HP 432 435 This response is the same as a square law detector so all the comments above for such detectors apply to power meters Setting the desired power with non autoranging meter HP 432 435 is straightforward Assume 3 dBm is desired at the power sensor Set the power meter on the 4 5 dBm range so the desired power is 2 dB below full scale Since the RF power changes 1 2 dB for each 1 dB reference change set the reference for 4 dBV Auto ranging meters e g HP 436 must be used in their range hold modes to prevent range change during blanking or other RF off intervals To lock the meter to the desired range internal leveling must be used Adjust the HP 8340B 41B output power until the meter is on the desired power range then press range hold As an example consider the HP 436 The HP 436 changes ranges every 10 dB so if 8 dBm is desired the reference must be set for 8 dB below full scale REF 16 dBV with the HP 436 locked on the 10 to 0 dBm range Caution the HP 436 range change circuits have intentional hysteresis Setting the power to 0 dBm may place the meter on either the 10 to 0 range or the 0 to 10 range For no ambiguity force the meter to the middle of the range 5 dBm 5 dBm etc then press range hold POWER dBm Display used with the Attenuator So
112. lained in the following paragraph defines the address for a circuit board or memory register that is accessible via the internal I O bus The channel values range from 0 to 15 Channel and subchannel addresses are listed in the optional Component Level Service Manual Press SHIFT GHz dB m then enter a numerical value between 0 15 followed by any terminator key SHIFT MHz sec HP IB SHMZ allows the I O subchannel to be specified Press SHIFT MHz sec then enter a numerical value followed by any terminator key SHIFT kHz msec HP IB SHKZ allows a numerical value to be written to the address defined by the channel and subchannel The appropriate numerical value is explained in the introduction of the optional Component Level Service Manual Press SHIFT kHz msec enter a numerical value followed by any terminator key SHIFT Hz AUTO HP IB SHHZ allows a numerical value to be read from the address defined by the channel and subchannel Press SHIFT Hz AUTO and the numerical data will appear in the ENTRY DISPLAY The introduction of the optional Component Level Ser vice Manual describes the interpretation of this data Figure 3 10 Entry Keys 2 of 2 Operating Information 3 27 Sweep and Trigger Keys DESCRIPTION Continuous single or manual sweeps and internal external or power line triggering are controlled by these keys Additionally display blanking penlift and three diagnosti
113. lanation of each key follows GHz dB m HP IB GZ or DB selects either gigahertz for a frequency function decibels or dBm for a power function MHz sec HP IB MZ or SC selects either megahertz for a frequency function or sec onds for a sweep time function kHZ msec HP IB KZ or MS selects either kilohertz for a frequency function or millise conds for a sweep time function Figure 3 10 Entry Keys 1 of 2 3 26 Operating Information HP 8340B 41B HZ AUTO HP IB HZ or AU selects hertz for a frequency function AUTO affects SWEEP TIME FREQ STOP and CW RES Press SWEEP TIME then AUTO to obtain the shortest possible sweep time for that frequency span press SHIFT CF then AUTO to couple the FREQ STOP increment size to the AF frequency span all of these shifted functions are explaiend in Figure 3 7 When one of the AUTO coupled functions is active AUTO or its complement which indicates that AUTO is not active appears in the ENTRY DISPLAY SHIFT terminator key allows direct electrical access to the internal circuits registers and buffers of the HP 8340B 41B These tremendously powerful functions are comprehensively explained in the optional Component Level Service Manual however a brief explanation follows HP 8340B 41B SHIFT GHz dB m HP IB SHGZ allows the I O channel to be specified The I O chan nel along with the I O subchannel exp
114. lator The integrator output continues to change until its input is zero which means the detector voltage is balancing the ALC input voltage The time required to cancel an error is about 70 usec 4 usec with AM on or when sweeping fast under which conditions a smaller value of C is switched into the circuit DETECTOR OUTPUT INTEGRATOR 1 0V ERROR VOLTRGE TO LINERR 2 2v MODULRTOR INTEGRATE HOLD SWITCH RLC INPUT 1 8V Figure 3 35 Error Detection and Modulator Drive Consider now pulse operation with a period of 1 msec The detector S H measures a pulse and holds its value until the next pulse Assuming an error is present the integrator responds to that error reaching the proper modulator drive in about 40 usec Since the detector S H is still holding the error from the last pulse the integrator keeps changing until the next pulse overshooting its mark and causing instability For this reason the integrate hold switch is only closed during a pulse During the period beween pulses the switch is opened thus the integrator input is zero so the modulator drive doesn t change This assures that the amplitude at the beginning of the next pulse is the same as at the end of the previous pulse Corrections take place only during the pulses until equilibrium is reached Since this may cause very long response times for narrow pulses the integrate hold switch is held closed a minimum of 10 us per pulse for pulses narrower than t
115. ly six ACA aaa SI ake 3 50 Power dBm Display used with AM 3 108 3 24 Power Line Module 3 51 Dynamic Range 3 109 Bandwidth for AM Applications 3 109 Page PULSE MODULATION 3 110 9 1 Dy MOda MACHON E Sample and Hold Leveling 3 110 HP IB PROGRAMMING INFORMATION Response Time 3 114 Unleveled Mode used with Introduction Qt 3 52 Pulse Modulation D 9 24 Interconnective Cabling 3 52 Input Characteristics 3 114 Instrument Addresses 3 52 Pulse Envelope 3 415 HP IB Instruments Nomenclature 3 52 Source Match 3 115 Programming the 83408 418 3 53 Video Feedthrough 3 115 HP IB Command Statements arte 3 53 SLOW RISE TIME PULSE MODULATION FOR HP 8340B 41B Programming Codes 3 59 SCALAR NETWORK ANALYZERS 3 116 Programs that Duplicate Front Panel Operations 3 59 Figure Page Using the Rotary KNOB 3 63 3 29 ALC Loop Block Diagram 3 99 Using Keys that Toggle ON OFF 3 63 3 30 Reverse Power Effects 3 101 Operator s Programing Check 3 63 3 31 Typical Unleveled Unique HP IB Programming Codes 3 64 Modulation Response 3 103
116. m that instrument like spokes in a wheel or in a linear pattern like boxcars in a train or in any combination pattern However there are certain restrictions e Each instrument must have a unique HP IB address ranging from 0 30 decimal Figure 3 12 SHIFT LOCAL explains HP IB addressing for the HP 8340B 41B Figure 3 20 HP IB Connector 1 of 2 HP 8340B 41B Operating Information 3 45 3 46 In a two instrument system that uses just one HP IB cable the cable length must not exceed 4 metres 13 feet e When more than two instruments are connected on the bus the cable length to each instrument must not exceed 2 metres 6 5 feet per unit The total cable length between all units cannot exceed 20 metres 65 feet Hewlett Packard manufactures HP IB extender instruments Models 37201A 37203A L that over come the range limitations imposed by the cabling rules These extenders allow twin pair cable operation up to 1000 metres 3 280 feet and telephone modem operation over any distance HP Sales and Service offices can provide additional information on HP IB extenders The codes next to the HP IB connector describe the HP IB electrical capabilities of the HP 8340B 41B using IEEE Std 488 1978 mnemonics HP IB GP IB IEEE 488 and IEC 625 are all electrically equiv alent Briefly the mnemonics translate as follows SH1 Source Handshake complete capability AH1 Acceptor Handshake complete capability
117. mbers The USING command is followed by image items that precisely define the format of the output these image items can be a string of code characters or a reference to a statement line in the computer program Image items are explained in the programming codes where they are needed Notice that this syntax is virtually identical with the syntax for the ENTER statement that follows A BASIC example 100 OUTPUT 719 programming codes The many programming codes for the HP 8340B 41B are listed in Tables 3 1 and 3 2 and are explained in the Programming Codes subsection Related statements used by some computers CONTROL CONVERT IMAGE IOBUFFER TRANSFER HP 8340B 41B Operating Information 3 57 Enter Enter is the complement to OUTPUT and is used to transfer data from the addressed instrument to the controller The syntax is device Ne Mes MES line variable number variable ENTER is always used in conjunction with OUTPUT such as 100 OUTPUT 719 programming codes 110 ENTER 719 complementary codes ENTER statements are commonly formatted which requires the secondary command USING and the appropriate image items The most used image items involve end of line EOL suppression binary inputs and literal inputs For example 100 ENTER 719 USING 2 suppresses the EOL sequence and indicates that variables A B and C are to be filled with binary B data As ano
118. me external leveling applications require low output power from the HP 8340B 41B for example leveling the output of a 30 dB amplifier to a level of 10 dBm In this application the output of the HP 8340B 41B is around 40 dBm when leveled At some frequencies this level is beyond the range of the ALC modulator alone If so the OVERMOD annunciator lights Inserting 40 dB of step attenuation results in an ALC level of 0 dBm which is well within the range of the ALC At 26 5 GHz where only 1 dBm is available 8340B 30 dB attenuation is a better choice as it results in an ALC level of 10dBm This gives a margin for AM or other functions that vary the power level HP 8340B 41B Operating Information 3 105 10 V 20 dBV 10 dBV 1 0V 10 dBV
119. ments to receive a new command from the controller Typically this is an initialization command used to place the bus in a known starting condition The syntax is interface where the interface select code is the computer s HP IB 1 0 port which is typically port 7 Some BASIC examples 10 ABORT 7 100 IF V gt 20 THEN ABORT 7 Related statements used by some computers ABORTIO used by HP 80 series computers HALT RESET Remote Remote causes an instrument to change from local control to remote control In remote control the front panel keys are disabled except for the LOCAL key and the POWER switch and the amber REMOTE annunciator is lighted in the ENTRY DISPLAY The syntax is REMOTE selector where the device selector is the address of the instrument appended to the HP IB port number Typically the HP IB port number is 7 and the default address for the HP 8340B 41B is 19 so the device selector is 719 Some BASIC examples 10 REMOTE 7 which prepares all HP IB instruments for remote operation although nothing appears to happen to the instruments until they are addresed to talk or 10 REMOTE 719 which effects the HP IB instrument located at addres 19 or 10 REMOTE 719 721 726 715 which effects four instruments that have addresses 19 21 26 and 15 Related statements used by some computers RESUME Operating Information HP 8340B 41B Local Lockout Local Lockout can be used in conju
120. mpleted the instrument behaves exactly as with SHIFT METER In this mode the attenuator is set automati cally For decoupled operation while unleveled the SHIFT METER mode must be used EXTERNAL LEVELING In externally leveled operations the output power from the HP 8340B 41B is detected by an external sensor The output of this detector is returned to the HP 8340B 41B s leveling circuits and the output power is automatically adjusted to keep the power constant at the point of detection Figure 3 32 shows a basic external leveling arrangement The output of the detected arm of the splitter or coupler is held constant if the splitter response is flat then the output of the other arm will be constant also This arrangement offers superior flatness over internal leveling especially if long cables are involved For best flatness a good resistive splitter with power meter detection should be used HP 83408 418 LEVELED OUTPUT POWER SPLITTER OR DIRECTIONAL COUPLER CRYSTAL DETECTOR OR POWER METER Figure 3 32 Typical External Leveling Hookup Reference to Figure 3 29 inciates that when externally leveled the power level feedback is taken from the external detector input rather than the internal detector This feedback voltage is what the loop is trying to control For a given ALC input the loop will adjust its output until the feedback is for instance 10 mV The type of coupler or detector has no influence on thi
121. n off diagnostics Turn off all markers Marker sweep M1 M2 Set power level step Enable HP 8756A 8757A compatability Decouple ATN ALC Remove save lock Blank displays Display fault diagnostic Control reference level ZOOM function Equivalent Key Ref Figure POWER LEVEL 3 7 PULSE 3 14 3 15 PWR SWP 3 17 RECALL 0 9 3 12 RF 3 17 PEAK 3 17 CONT 3 11 SINGLE 3 11 MANUAL 3 11 MHz sec 3 10 SHIFT 3 7 SHIFT INT 3 16 SHIFT XTAL 3 16 SHIFT METER 3 17 SHIFT AMTD MKR 3 17 SHIFT ALT 3 12 SHIFT AM 3 14 SHIFT CF 3 7 SHIFT CW 3 7 SHIFT ENTRY OFF 3 8 SHIFT START FREQ 3 7 SHIFT STOP FREQ 3 7 SHIFT INSTR PRESET 3 12 SHIFT M1 3 9 SHIFT M2 3 9 SHIFT M3 3 9 SHIFT M4 3 9 SHIFT M5 3 9 SHIFT OFF 3 9 SHIFT MKR SWEEP 3 9 SHIFT POWER LEVEL 3 7 SHIFT PULSE 3 14 3 15 SHIFT PWR SWP 3 17 SHIFT RECALL 3 12 SHIFT CONT 3 11 SHIFT MANUAL 3 11 SHIFT SLOPE 3 17 3 7 SHIFT SWEEP TIME Table 3 2 HP 8340B 41B Programming Codes 3 of 4 SHSV Lock save recall SHIFT SAVE 3 12 SHRF Same as SHA1 SHIFT RF 3 17 SHRP Tracking calibration SHIFT PEAK 3 17 SHT1 Test displays SHIFT FREE RUN 3 11 SHT2 Bandcrossing penlift SHIFT LINE 3 11 SHT3 Display unlock indicators SHIFT EXT 3 11 SHGZ dt IO channel SHIFT Ghz dB m 3 10 SHMZ dt IO subchannel SHI
122. n with any HP power meter on any range When turning on the RF power either when unblanking or using the RF key the slow response of the power meter can cause serious power overshoot in some external leveling systems This overshoot may damage active devices or some power sensors To prevent this problem in the HP 8340B 41B a slow turn on circuit is employed when METER leveling is selected This circuit raises the power slowly over a period of 2 seconds The sweep generator automatically waits for this settling time to end before beginning a sweep HP 8340B 41B Operating Information Amplitude modulation is possible when power meter leveled The system provides linear and is dc coupled For rates below 0 7 Hz the leveling is done via the power meter sensor and behaves just like internal leveling Above 0 7 Hz feedback from the power meter rolls off and is replaced by feedback from the HP 8340B 41B s internal detector Thus high frequency envelopes are under control of the internal detector while the power meter controls the power level The modulation depth is still accu rate and the bandwidth is nominally 80 kHz The power sensor is not following the modulation hence it will average the power When modulating with sinusoid symmetric about the average output power increases by 50 for 100 AM The power sensor senses this increase and reduces the HP 8340B 41B s output until the average equals what the power was with no modulat
123. nal the power meter must be zeroed in the presence of the noise Connect the power meter then press RF to shut off any RF output although the RF is off the noise is still present and the power meter can now be zeroed When going to frequencies above 2 3 GHz the meter must be re zeroed The broadband noise is attenuated by the step attenuator along with the desired signal Noise makes a 0 05 dB contribution at ALC 10 dBm UNLEVELED MODE The HP 8340B 41B has a power control mode in which the leveling feedback loop is opened The ALC inputs are used to directly control the RF modulator Pressing SHIFT METER activates this mode The annunciators on the leveling mode keys are extinguished the UNLEVELED annunciator is lighted and the ENTRY DISPLAY shows dB MOD As with the decoupled mode the attenuator is set via the STEP keys and the modulator entry is made with keypad or KNOB The entry range is 0 to 100 dB The modulator entry is an approximately cali brated relative indication because the modulator s gain and maximum output change with frequency See Figure 3 31 AM works in this mode with unspecified distortion Pulse modulation works Power sweep works with linearity as depicted in Figure 3 31 The POWER dBm display still indicates actual output power As with other leveling modes it indicates the sum of level and attenuation with useful accuracy down to ALC levels of 20dBm S
124. nal leveling signal The signal requirements are listed in the specification tables in Section See the Operating Guide Externally Leveling the HP 8340B 41B Synthesized Sweeper located at the end of Section III for detailed information about external leveling procedures INT HP IB 1 selects internal leveling of the HP 8340B 41B The specifications tables in Section list the maximum leveled power for each frequency band and other power function restraints SHIFT INT HP IB SHA bypasses the ALC automatic leveling control and allows the user to select a power level to be set in the unleveled mode The benefit of this function is that an unleveled output power level can be set via HP IB while allowing the synthesized sweeper to be pulse modu lated with no limit to the minimum pulse reptition frequency and complete use of the 100 kHz AM bandwidth while simultaneously pulse modulating Press SHIFT INT POWER SEARCH XXX dBm will appear in the entry display The previous internally leveled power will be set automatically To enter a different power use KNOB STEP keys or numeric keypad terminate with the dBm key XTAL HP IB 2 activates external crystal leveling of the HP 8340B 41B A portion of the RF output derived from a coupler or a splitter must be detected with the detected output being delivered to the EXT INPUT BNC connector thus forming an output input feedback loop the loop typically has 80
125. nction Parity 0 Control Interrupt SRQ SDC GET SCG 0 Mask Not HP IB Control REN SRQ ATN DAV NDAC NRFD Applicable Control Lines Not HP IB DIO8 DIO7 0106 DIOS DIO4 DIO3 DIO2 0101 Applicable Data Lines HP 9826 9836 926 936 HP IB READIO Register 23 Control Line Status Most Significant Bit Least Significant Bit ATN DAV NDAC NRFD EOI SRQ IFC REN True True True True True True True True Value 128 Value 64 Value 32 Value 16 Value Value 2 Value Only if addressed to TALK else not valid Only if Active Controller else not valid HP 9826 9836 926 936 HP IB READIO Register 31 Bus Data Lines Most Significant Bit Least Significant Bit HP 9826 9836 926 936 HP IB WRITEIO Register 31 Data Out Register Most Significant Bit Least Significant Bit Figure 3 28 Representative Control Registers Operating Information HP 8340B 41B The bits the control registers are set using this statement CONTROL 7 register number decimal value of True bits To set the bits and the corresponding HP IB lines True 1 use their corresponding decimal values BIT 7 6 5 4 3 2 1 0 DECIMAL 128 64 32 16 8 4 2 1 For example 100 CONTROL 7 2 16 sets bit 4 decimal 16 of control register 2 True while all other bits in that register are set False As another example 100 CONTROL 7 3 63 sets bits 0 5 True decimal 1 2 4 8 1
126. nction with REMOTE to disable the front panel LOCAL key With the LOCAL key disabled only the controller or a hard reset by the POWER switch can restore local control The syntax is interface LOCAL LOCKOUT A BASIC example 10 REMOTE 719 20 LOCAL LOCKOUT 7 Local Local is the complement to REMOTE causing an instrument to return to local control with a fully enabled front panel LOCAL syntax is LOCAL selector Some BASIC examples 10 LOCAL 7 which effects all instruments in the network or 10 LOCAL 719 for an addressed instrument address 19 Related statements used by some computers RESUME Clear Clear causes all HP IB instruments or addressed instruments to assume a cleared condition with the definition of cleared being unique for each device For the HP 8340B 41B 1 Both status bytes are reset to zero 2 All pending output parameter operations such as those associated with OA OP and OR codes are halted 3 The parser the software that interprets the programming codes is reset and now expects to receive the first character of a programming code HP 8340B 41B Operating Information 3 55 The syntax is s selector Some BASIC examples 10 CLEAR 7 to clear all HP IB instruments or 10 CLEAR 719 to clear an addressed instrument Related statements used by some computers RESET CONTROL SEND Trigger Trigger initiates a single event such
127. ng paragraph Press PULSE a second time to turn off the function SHIFT PULSE HP IB SHPM turns on pulse modulation allowing proper operation with HP 8755C 8756A and 8757A scalar network analyzer The scalar analyzers 27 8 Khz square wave modulation output is connected to the HP 8340B 41B PULSE input When the SHIFT PULSE mode is activated the RF output of the HP 8340B 41B is modulated by the 27 8 kHz square wave This capability is present on all HP 8340B 41B s regardless of option configuration Pressing PULSE HP IB PMO will turn off this function This mode may be used for other purposes providing 2 rise and fall times for pulse widths wider than about 7us AM HP IB turns on amplitude modulation AMO turns off the function activates the ampli tude modulation function Amplitude modulation allows the pre attentuated RF output of the HP 8340B 41B to be continuously and linearly varied between 80 dBm and the maximum power avail able at a rate determined by the AM input described in Figure 3 15 Amplitude and pulse modulation can be in effect simultaneously Press AM a second time to turn off the function FM HP IB FM1 turns on frequency modulation FMO turns off modulation activates the frequency modulation function Frequency deviation is dependent on the magnitude of the input signal Pressing FM a second time turns off the function FM sensitivity is either 1 MHz volt or 10 MHz volt and is s
128. o 5 V dc Figure 3 25 Pin Out Data lines DIO1 DIOS8 These are the eight Data Input Output lines Data is transceived on the eight HP IB data lines as a series of eight bit bytes with DIO1 being the least significant bit LSB 0108 being the most significant MSB The meaning of each byte is arbitrary being different for each type of instrument The rate of data transfer is controlled by the handshake sequence Handshake lines DAV NRFD NDAC These three lines control the data transfer process DAV Data Valid line is high False data not valid or low True data valid to indicate the validity of the signals on the DIO lines NRFD Not Ready for Data line indicates whether the instruments receiving data are prepared to accept that data NRFD is either low True the instruments are not ready for data or high False the instruments are ready for data NDAC Not Data Accepted line indicates whether the data receiving instruments have accepted the transmitted data NDAC is either high False the data has been accepted or low True the data has not been accepted Figure 3 26 illustrates a representative handshake timing sequence HP 8340B 41B Operating Information 3 83 3 84 DIO LINES ONLY ONE LINE IS SHOWN RS AN EXAMPLE p s Period in which data Period which all Period in uhich 22 is guaranteed SS listeners become all listeners A to be valid ready for data accept
129. o reach operating temperature The STANDBY position of the POWER switch maintains power to the oven heater thus keeping the oven warm and the crystal oscillator ready for immediate operation Although the HP 8340B 41B can be operated with a cold crystal oscillator the instrument might not fully comply with specifications until the proper operating temperature is achieved UNLK red annunciator lights when the HP 8340B 41B s output signal is no longer phase locked to the 10 MHz reference oscillator Press SHIFT EXT which will cause OSC REF M N HET YO N2 1 to appear in the ENTRY DISPLAY The flashing letters indicate which oscillator is not phase locked Refer to the In Case of Difficulty Section DIAGNOSTICS Press and hold INSTR PRESET to light the seven annunciators then release INSTR PRESET and press SHIFT FREE RUN which will light every LED segment and show the entire ENTRY DISPLAY character set Press INSTR PRESET or cycle the POWER switch to end this diagnostic routine This diagnostic also tests the three other displays NOTE INSTR PRESET will restore the instrument to its standard starting condition Cycling the POWER switch will restore the instrument to its previous state Figure 3 6 Entry Display 2 of 2 3 18 Operating Information HP 8340B 41B Function Keys DESCRIPTION This group of keys selects frequency mode power level sweep time and associated functions PAN
130. op typical bandwidth 0 7 Hz Press METER which will cause after a brief delay ATN xx dB REF xx xx dBV where x is the last entered value to appear in the ENTRY DISPLAY Use the rotary KNOB or the numerical keys with the dB m terminator key to set the REFerence level and the STEP keys to set the ATN while watching either the POWER dBm display allowing for coupler or splitter losses or the power meter The Externally Leveling the HP 8340B 41B Synthesized Sweeper Operating Guide located at the end of this section fully explains power meter leveling SHIFT METER HP IB SHA3 bypasses the ALC automatic leveling control to allow direct con trol of the linear modulator circuit This is useful when very narrow pulses are being generated in pulse modulation mode In this mode there is no limit on the minimum pulse repitition frequency Press SHIFT METER and dB mod x x dB where x is the last entered value will appear in the ENTRY DISPLAY To set the power place the HP 8340B 41B in CW mode or in pulse modulation mode with pulses wider than 2usec Then use the STEP keys to set the attenuator and the rotary KNOB or numerical keys with dB m terminator key to set the MOD linear modulator as follows Set MOD entry at 0 dB increment ATN until the POWER dBm display shows a level 5 dB to 15 dB higher than the desired output power then reduce the power to the desired level by changing
131. p listen addresses of specified instruments An HP IB instrument may have any unique address in the range 00 30 decimal The distinction between a listen address and a talk address is made in bits 5 and 6 using address 19 as an example BIT 7 6 5 4 3 2 1 0 TALK X 1 01 0 0 1 1 LISTEN X 01 1 00 1 1 The corresponding ASCII codes for the available HP IB addresses are listed in Table 3 3 LF Line Feed ASCII decimal 10 3 86 Operating Information HP 8340B 41B LLO Local Lockout disables the instruments LOCAL reset key LLO is accomplished by ASCII DCI decimal 17 My Listen Address listen address of the controller MTA My Talk Address talk address of the controller PPC Parallel Poll Configure not used by the HP 8340B 41 B PPU Parallel Poll Unconfigure not used by the HP 8340B 41B SC System controller SCG Secondary command group also abbreviated SEC SDC Selected Device Clear causes addressed instruments to clear to an instrument defined state accomplished by ASCII EOT decimal 4 SPD Serial Poll Disable accomplished by ASCII EM decimal 25 SPE Serial Poll Enable accomplished by ASCII CAN decimal 24 A serial polled instrument responds with a byte of information with each bit corresponding to a specific instrument function TA Talker active state TAD Talk Address of a specified device see LAG for related information Take Control transfers active controller responsib
132. p sweep frequencies then outputting SM to activate manual sweep mode A BASIC example 100 OUTPUT 719 IP FASGZ 5 1 2 FB15G2 EK SM This example sets a 5 GHz start frequency a 1 MHz frequency step size and a 15 GHz stop frequency The last two codes in line 100 enable the rotary KNOB and activate manual sweep mode In addition to KNOB control of the sweep UP and DN can be used and would have a 1 MHz step size There are two significant differences between manual sweep and a stepped CW sweep 1 Thesweep voltage ramp see Figures 3 13 and 3 18 SWEEP OUTPUT is 0 10 volts for both modes however in CW mode 0 volts always corresponds to 10 MHz and 10 volts always corresponds to 26 5 GHz in the case of the HP 8341B 7 55v at 20 0 GHz while in manual sweep mode 0 volts corresponds to the start frequency and 10 volts corresponds to the stop frequency In both cases the sweep voltage at intermediate frequencies is a linear interpola tion of the frequency span i e a frequency half way between the start stop limits would have a corresponding sweep voltage of 5 volts 2 bandcrossing in CW mode always occur at preciesely 2 4 GHz 7 0 GHz 13 5 GHz and in the case of the HP 8340B 20 0 GHz In manual sweep mode the bandcrossing points have 200 MHz of flexibility and could for example accomplish a 13 45 20 05 GHz sweep in single band instead of the three bands required in stepped CW 8340B The HP 8340B 41B automaticall
133. paragraph is a related function SHIFT PEAK HP IB SHRP is a more extensive version of peaking PEAK which requires fraction of a second to implement aligns the output filter with a single CW frequency while SHIFT PEAK aligns all of the YTM tracking calibration constants and requires 5 10 seconds to implement Use SHIFT PEAK to enhance the power output and spectral purity of swept modes and to improve tracking performance especially in harsh environments having wide temperature variations Press SHIFT PEAK which will cause AUTO TRACKING to appear in the ENTRY DISPLAY AUTO TRACKING will disappear after 5 10 seconds when the calibration has been completed Figure 3 17 RF Keys Output 1 of 3 HP 8340B 41B Operating Information 3 39 PWR SWEEP HP IB PS1 turns on power sweep PSO turns off the function allows the power output to be swept when the HP 8340B 41B is in CW mode This is the procedure 1 Select a CW frequency as explained in Figure 3 7 2 Press SHIFT PWR SWEEP which decouples the attentuator ATN from the automatic leveling control ALC and displays the ATN and ALC values in the ENTRY DISPLAY The ALC range is 20 dBm to an upper value that depends on frequency see the specifications given in Section I 3 Use the STEP keys to set the value of the and the KNOB or numerical keys with dB m terminator key to set the ALC for the starting power level
134. perating Information 3 69 OK d Output last locKed frequency indicates the last phase locked frequency of the HP 8340B 41B in Hz A BASIC example 100 OUTPUT 719 CWEK 110 PAUSE 120 OUTPUT 719 OK 130 ENTER 719 F 140 PRINT LAST FREQUENCY F HZ In line 100 the rotary KNOB is enabled EK and used to adjust the CW frequency After complet ing the frequency adjustment press CONTINUE on the computer and the last phase lock fre quency the current CW frequency in this example is read and printed OL 123b Output Learn data is used on conjunction with IL Input Learn data to save and recall specific instrument operating configurations is similar to SAVE RECALL except the func tion that was active prior to OL storage is once again active after an IL recall SAVE RECALL is restricted to nine instrument configurations and uses the memory of the HP 8340B 41B while OL IL uses the computer s memory and is restricted only by the size of that memory The learn data consists of 123 bytes of information This information is heavily coded and densely packed for conciseness so a byte by byte deciphering is not recommended use OP to obtain information about a specific function or state This is a typical BASIC program using Ol and IL 10 DIMASIT1231 100 OUTPUT 719 programming codes 110 REM 120 REM STORE THIS INSTRUMENT STATE 130 OUTPUT 719 DL 140 ENTER 719 USING
135. requency only The source match at other frequencies is that of the unleveled RF hardware In this case this is a YIG filter whichis a good reflection for anything more than about 20 MHz off center and not much better within its passband The match is good only for signals at the output frequency plus or minus the leveling loop bandwidth Thus a CW reflection will be absorbed A time varying reflection as from a reflective modulator may contain modulation side bands outside the leveling loop bandwidth If so these sidebands may be re reflected When pulse modulating any reflection of the pulse will contain sidebands far outside the loop bandwidth so the leading edge of the reflection will be re reflected In this manner a poorly matched system can gener ate very poor envelopes anywhere in the system not only at the source Performance is improved by padding between the reflections At the source if output powers above 10 dBm are in use coupled mode results on 0 dB RF attenuation If enough power is available decoupled mode may be used to improve the HP 8340B 41B s source match by inserting 10 dB attenuation and using a 10 dB high ALC level Video Feedthrough Video feedthrough is a low frequency signal at the modulation rate which is superimposed on the RF envelope See Figure 3 37 If large enough video feedthrough can disturb mixer balance amplifier bias crystal detector output etc Since itis low frequency energy itcan distrub s
136. rogramming codes GZ MZ KZ HZ DB SC and MS re used as terminators because they also serve as units scalars Alternatively a comma oran asi LF decimal 10 can be used as a terminator which will cause the HP 8340B 41B to scale the corr sponding function to the fundamental units of Hertz seconds or dB m parenthesis indicate codes that cause the HP 8340B 41B to output information for a subsequent input by the computer with the format of that information being indicated by the parenthetical letters For example code listing OC 3d indicates that 3 decimal values should be read as a result of the OC command 100 OUTPUT 719 0 110 ENTER 719 A B C As lola example code listing OM 8b indicates that 8 binary bytes should be read 100 OUTPUT 719 Om 110 ENTER 719 USING B1 B2 B4 B5 B6 B7 B8 The image parameters in line 110 are explained in the preceeding b binary data section follows the codes that have special suffix requirements consult the detailed explanation of the code for further information Operating Information 3 61 3 62 Using the Rotary KNOB The rotary KNOB can also be enabled for interactive programs The KNOB is normally disabled when the HP 8340B 41B is in REMOTE however the programming code reenables the KNOB 80 REM EK ALLOWS THE KNOB TO CONTROL PL 90 OUTPUT 719 EKPL 100 PAUSE 110 REM EK ALLOWS THE KNOB CONTROL CW 120 OUT
137. roper combination of ALC and attenuator is decided by the internal microprocessor the user need only set the desired power in the ENTRY DISPLAY via the POWER key 1 HP 8340B s equipped with Options 001 or 005 are not supplied with the step attenuator 3 98 Operating Information HP 8340B 41B UNLEVELED RF THE RF POWER LEVEL HERE IS THE ALC LEVEL AND HAS A RANGE OF 28 TO 2 4 PULSE INPUT ALC INPUTS LEVELED P B TO m RF LEVEL RF 90dB STEP 2a8 CONTROL ATTENUATOR CIRCUITS 1 dB STEPS INTERNAL DETECTOR ALC ATTENUATOR 20 TO SETTING ATTENUATOR 28dBm to SETTING POWER LEVEL FEEDBRCK POWER ENTRY DISPLAY POWER dBm DISPLAY 20 TO 11 dBm INTERNRL EXTERNAL LEVELING EXTERNAL MODE UNLEVELED dc REPRESENTING DETECTOR ALC LEVEL INPUT 28 TO Figure 3 29 ALC Loop Block Diagram POWER dBm Display If the requested power is greater than can be provided the level control loop will provide maximum available power and light the UNLEVELED annunciator When unleveled the output power does not equal the value shown in the ENTRY DISPLAY The internal detector is monitoring the actual power however and its output voltage controls the POWER dBm display The detector voltage is interpreted to give ALC level and the attenuator setting is subtracted to yield actual output power ev
138. rs Talker A talker is a device that is capable of transmitting data or commands to other instruments To avoid confusion an HP IB system allows only one device at a time to be an active talker 3 52 Operating Information HP 8340B 41B Controller A controller is an instrument typically a computer that is capable of managing the various HP IB activities Only one device at a time can be an active controller PROGRAMMING THE HP 8340B 41B The HP 8340B 41B can be entirely controlled by a computer although the line POWER switch must be operated manually All functions that are initiated by front panel keystrokes local operation can also be initiated by an HP IB computer additionally several functions are possible only by computer remote control Computer programming procedures for the HP 8340B 41B involve selecting an HP IB command statement then adding the specific HP 8340B 41B programming codes to that statement to achieve the desired operating conditions The programming codes can be categorized into two groups Those that mimic front panel keystrokes and the unique codes that have no front panel equivalent In the programming explanations that follow specific examples are included that are written in a generic dialect of the BASIC language BASIC was selected because the majority of HP IB computers have BASIC language capability however other languages can also be used Hewlett Packard pub lishes a series of Programming No
139. rvo motor of an X Y recorder to pause while the HP 8340B 41B crosses a frequency band switchpoint The X Y recorder Operating Guide located at the end of Section III explains the interaction of recorders with the HP 8340B 41B PENLIFT OUTPUT For operation with X Y recorders PENLIFT disables an X Y recorder s ability to lower its pen during sweep retrace If SHIFT LINE is pressed on the front panel PENLIFT will also disable the pen during forward sweep band switchpoints Because of X Y recorder limitations PEN LIFT will always disable the X Y recorder s pen at sweep times under 5 seconds PENLIFT enables pen operation by providing a current path to ground for the X Y recorder s pen solenoid The voltage at the PENLIFT output in this state will be approximately 0 Vdc Circuit imped ance in this state is approximately 5 Ohms PENLIFT disables pen operation by not providing a current path to ground for the X Y recorder s pen solenoid The voltage on the PENLIFT output will be equal to the X Y recorder s pen solenoid supply voltage Circuit impedance in this state is very high NEG BLANKING provides a negative rectangular pulse approximately 5 volts into 2 KQ during retrace and band switchpoints when the HP 8340B 41B is sweeping Z AXIS BLANK MKRS supplies a positive rectangular pulse approximately 5 volts into 2 dur ing the retrace and switchpoints when the HP 8340B 41B is sweeping This output also supplies a 5 volt pulse w
140. s if the loop is able it will drive the feedback to the requested level Since there is no inherent relationship between ALC input and the amount of externally leveled RF power the power level ENTRY DISPLAY shows the feedback voltage which the loop is seeking This voltage is called the reference voltage and is displayed alongside the attenuator setting as ATTN _____ __ dBV The entry units are dB relative to 1 volt where 1 00 V OdBV 0 1 V 20 dBV etc As with the decoupled mode of internal leveling the REF is set with the keypad or KNOB while the attenuator is set with the STEP keys The attenuator will normally be left at 0 dB Its use is described below 3 104 Operating Information HP 8340B 41B The reference voltage may be set over range of 66 0005V to 6 2 00V This wide range accommodates a variety of detectors and leveling situations The input accepts either positive or negative voltages automatically For example with REF 20 dBV the loop will level with an input of either 0 1V or 0 1V The input will accept overloads of 25 volts with no damage The input resistance is 1 MQ Figure 3 33 shows the input power versus output voltage characteristics for typical HP crystal detectors From the chart the leveled power at the crystal detector input resulting from any reference setting may be determined The range of power adjustment is approximately 30 dBm to 18 dBm Det
141. s a capacity of 9 memory registers located in the HP 8340B 41B IL OL data is stored in the computer s mass storage device IL is explained under the OL programming code KR Keyboard Release is used with the NA code If NA bit 1 is set True 1 the 8340B 41B front panel keys are in a lock and release mode In this mode the keyboard is locked disabled after any one key has been pressed and remains locked until released by the KR code The typical loop program involves three steps 1 Determine which key was pressed by using the OM code 2 process the key closure information 3 use KR to relese the keyboard and return to step 1 NAb Network Analyzer configuration established the operating modules that are used when the HP 8340B 41B is interfaced with certain network analyzers The modes are established by adding a binary or decimal number to the NA code where the bits of the number are deciphered as follows Bit 0 set true 1 Enable network analyzer mode with the following features 1 Enable group execute trigger GET to start a sweep after a mid sweep if in analog sweep mode Use Stop Frequency to calculate the end of the band e Disable HP 8340B 41B detection of sweep event markers bandcrossing points and sweep end point Do binary search to set sweep reset DAC 4 5 Issue end of sweep SRQ for mid sweep update 6 Disable automatic alternation when alternating in manual or CW non swept mode Ignor
142. s typically used to purge all instrument memory locations and registers after the HP 8340B 41B has been used in highly sensitive or classified applications This feature completely erases RAM memory filling RAM locations with zeros and then with ones It then sets all variables and SAVE RECALL reigsters to instrument preset values and downloads protected ERROM based Cal Constants into erased RAM into the Working Cal Constant memory area The instrument begins operation in the instrument preset mode NOTE Calibration Constants contain no frequency specific information Activating the Security Memory Erase Feature Locally Press SHIFT MHz 1 8 Hz SHIFT kHz 0 Hz Via HP IB SHMZ18HZ SHKZ0HZ INDICATORS INSTR CHECK 1 11 red LEDs light if the HP 8340B 41B fails the internal self test that occurs when INSTR PRESET is pressed If this happens refer to Section VIII Service for further instructions Figure 3 12 Instrument State Keys 3 of 3 HP 8340B 41B Operating Information 3 33 Power Switch Sweep Output DESCRIPTION The POWER switch and the SWEEP OUTPUT front panel BNC connector are described in this Figure PANEL LAYOUT STANDBY POWER SWEEP OUTPUT FUNCTIONS POWER SWITCH selects either ON or STANDBY Once the ac power line has been plugged in power is always being applied to all or part of the HP 8340B 41B In STANDBY power is applied to the crystal oscillator s oven to m
143. sed by the completion of numeric erly use the OA code to determine the value of the numerical entry Bit 2 SRQ caused by a change in the extended status byte status byte 2 affected by the RE coded mask see the RE code for an explanation of this masking Bit 3 SRQ caused by the completion of phase locking and the settling of the RF source use the OK code to determine the last lock frequency Bit 4 SRQ on end of sweep or mid sweep update in NA network analyzer code mode Bit 5 SRQ caused by HP IB syntax error Bit 6 SERVICE REQUEST by IEEE 488 convention the instrument needs service from the controller when this bit is set true Bit 7 SRQ caused by a change in the coupled parameters start frequency center frequency and sweep time Use the OC code to determine the new values of the coupled parameters Status Byte 2 Extended Status Byte Bit 0 Self test failed at power on or at Instrument Preset This bit remains latched until this status byte has been read or until cleared by the CS or CLEAR 719 commands Bit 1 Excessive amplitude modulation input Bit 2 Oven for the reference crystal oscillator is not at operating temperature Bit 3 External reference frequency was selected by the rear panel FREQUENCY STANDARD switch Operating Information HP 8340B 41B Bit 4 RF is unlocked UNLK appears the ENTRY DISPLAY Use OF to determine the source of the unlocked output This bit remains latched until
144. ses per revolution the KNOB is frequently referred to as an RPG rotary pulse generator in service literature SHIFT ROTARY KNOB SHIFT does not affect the rotary KNOB Figure 3 8 KNOB STEP Entry 1 of 2 3 22 Operating Information 8340B 41B STEP KEYS HP IB UP for up increment DN for down increment change the value of any active function by an incremental step Press any function key to activate that function then press either the up arrow or down arrow STEP key to incrementally change the value of that function Press and hold a STEP key for a repeat action The active function is always shown in the ENTRY DISPLAY SHIFT CF and SHIFT POWER LEVEL in Figure 3 7 explain the procedures for changing the size of the increment step although for sweep times the increment is a fixed 1 2 5 sequence After an INSTR PRESET the step size increments default to 1 10 of the current sweep width changing as the width changes for the FREQ STEP and to 10 00 dB for the LVL STEP SHIFT STEP KEYS SHIFT does not effect the STEP keys however the STEP keys are used for the shifted CW RES function CW RES is accomplished by pressing SHIFT CW then using the STEP keys to move the cursor left or right in the ENTRY DISPLAY SHIFT CW in Figure 3 7 explains the CW RES function INDICATORS ON is an LED that is lighted when the STEP keys and rotary KNOB are enabled not lighted when those
145. st results are available from the front panel or as a string of 32 characters over the HP IB These charac ters may be either 1 or O indicating respectively a passed or failed test In BASIC 100 DIM Test no C32 20 110 OUTPUT 719 SHM4 120 FOR I 1 0 32 130 READ Test no CI 140 DATA PROCESSOR TST ROM 1 CKSUM ROM 2 CKSUM ROM 3 CKSUM ROM 4 CKUSM RAM 1 RD WR RAM 2 RD WR EEROM 1 RD WR EEROM 2 RD WR 150 DATA RAM RD WR PIT CLED REG PIT RESPONDS IQ ADDR BUSS I0 DATA BUSS CONVERTER LEVEL REF DAC MAN SWP DAC RAMP 160 DATA RESET DAC LEVEL SWP DAC BND CROSS DAC SWP WIDTH DAC SWP RANGE V GHz CIRCUIT V GHz BNDATN BRK PNT 1 DAC BRK PNT 2 DAC 170 DATA ATN SLOPE DAC YO PRETUN DAC SWEEPTIME DAC NOT USED 427 INSTALLED 180 NEXTI 190 DIMDt 32 200 OUTPUT 719 210 ENTER 719 Dt 220 FORI 17TO 32 3 68 Operating Information HP 8340B 41B 230 11 1 THEN 240 IMAGE 134 10X PASS 250 PRINT USING 240 Test no CI 260 ELSE E 270 IMAGE 134 10X FAIL 280 PRINT USING 270 Test no CI 290 END IF 300 310 END Consult Section VIII Service for a detailed explanation of these diagnostic functions OF d Output Fault outputs a decimal value that can be decoded to determine which fault conditions have occurred These fault conditions are automatically
146. sted in the specifications Table 1 1 the UNELEVELED annunciator will light when the true maximum power level has just been exceeded To remedy an UNLEVELED condition either PEAK the instrument for CW or manual modes as explained in Figure 3 17 or reduce the requested power Figure 3 3 Power dBm Display 1 of 2 HP 8340B 41B Operating Information 3 13 Machine malfunction If the UNLEVELED annunciator lights and the cause is not a request for excessive power one or more of the power circuits are malfunctioning If this happens press INSTR PRESET which will restore standard instrument conditions then re enter the desired instrument configuration If the UNLEVELED annunciator remains lighted shut down the instrument and consult the In Case of Difficulty section in this manual Exception open loop operation The ALC can be bypassed by pressing SHIFT METER as described in Figure 3 16 Under these conditions the UNLEVELED annunciator is lighted but acts as a reminder in this case instead of a warning DIAGNOSTICS Test this display and the three other displays by pressing and holding INSTR PRESET which will cause the UNLEVELED annunciator to light then release INSTR PRESET and press SHIFT FREE RUN which will light every segment of the LED display 88888 Press INSTR PRESET or cycle the POWER switch to cancel this diagnostic test NOTE INSTR PRESET will restore the instrument to its standard st
147. sts may also be performed over the HP IB and results read by using the OD command see the HP IB PROGRAMMING SECTION of this Operating Information manual SHIFT M5 HP IB SHM5 turns off all diagnostic routines except the SHIFT FREE RUN display test MKR SWEEP HP IB MP1 activates the function MPO turns off the function causes the HP 8340B 41B to start sweeping at the frequency of marker M1 and stop sweeping at the frequency of marker M2 M2 must have a higher frequency than M1 If MKR SWEEP is activated when M2 is at a lower frequency than M1 the values of M1 M2 will be permanently interchanged Press MKR SWEEP again to exit from Marker Sweep and return to the previous sweep limits The LED above the key indicates whether the function is on lighted or off not lighted SHIFT SWEEP HP IB SHMP causes the sweep limits to permanently change to the fre quencies of M1 and M2 Repeated pressing of MKR SWEEP alone causes the HP 8340B 41B to toggle between M1 M2 sweeps and the previous sweep frequencies SHIFT MKR SWEEP eradicates the previous sweep values leaving only the M1 M2 frequencies OFF HP IB MO turns off deactivates any single marker Press any marker key M1 M5 then press OFF to deactivate that marker If OFF is pressed without first pressing a marker key the most recently active marker will be turned off The frequency value of the deactivated marker is
148. t the operator must retrace and the green LED by the SWEEP label will not light The resolution of the KNOB is 0 1 of the sweep span in either start stop or CF AF mode Frequencies in manual sweep are synthesized just as they are in CW mode Figure 3 11 Sweep and Trigger Keys 1 of 3 3 28 Operating Information HP 8340B 41B There two significant differences between MANUAL sweep and the sweep that can be obtained by having the KNOB control an active CW function 1 The sweep output voltage ramp see Figures 3 13 or 3 18 SWEEP OUTPUT is 0 10 volts in both modes but in CW mode 0 volts always corresponds to 10 MHz and 10 volts always corresponds to 26 5 GHz 7 55V at 20 GHz with HP 8341B while in manual sweep mode 0 volts corresponds to the start frequency and 10 volts corresponds to the stop frequency In both cases the sweep voltage at intermediate frequencies is a linear interpolation of the frequency span i e a fre quency half way between the start stop limits has a corresponding sweep voltage of 5 volts 2 The bandcrossing points in CW mode always occur at precisely 2 3 7 0 13 5 and in the case of the HP 8340B 20 0 GHz In manual sweep mode the bandcrossing points have 200 MHz of flexibility which is automatically used by the HP 8340B 41B for optimum performance for exam ple a 2 35 to 7 05 sweep could be accomplished without any band changes in manual sweep mode
149. t the time of entry If the start power is entered via the POWER LEVEL key the ALC is set no lower than 10 dBm limiting available power sweep range to 30 dB at 4 5 GHz or 11 dB at 26 5 GHz HP 8340B Using decoupled mode and setting the ALC to 20 dBm gives an additional 10 dB of sweep range although at 20 dBm start power uncertainty is degraded by 1 dB Decoupled mode is also useful when working with mixers Figure 3 30A shows a hypothetical setup where a HP 8340B 41B is providing the small signal to a mixer The HP 8340B 41B output is 8 dBm which in coupled mode results in ALC 8 dBm ATTN 0 dB The mixer is driven with an LO of 10 dBm and has LO to RF isolation of 15 dB The resulting LO feedthrough of 5 dBm enters the HP 8340B 41B s OUTPUT port goes through the attenuator with no loss and arrives at the internal detector Dependng on frequency it is possible for most of this energy to enter the detector Since the detector responds to its total input power regardless of frequency this excess energy causes the leveling circuit to reduce its output In this example the reverse power is actually larger than the ALC level which may result in the HP 8340B 41B output being shut off Figure 3 30B shows the same setup with decoupled mode used to give a 8 dBm output ALC 2 dBm ATTN 10 dB The ALC is 10 dB higher and the attenuator reduces the LO feedthrough by 10 dB Thus the detector sees 2 dBm desir
150. tage which is then displayed as power in a 500 system dBm 500 3 108 Operating Information HP 8340B 41B Therefore modulation inputs with no dc component do not cause the POWER dBm display to shift and this displayed number represents the power of the unmodulated carrier A power meter measure ment of output power changes with modulation present increasing 1 76 dB with 100 deep sinusoidal no dc component modulation Attempted deep modulation at high rates causes the POWER dBm display to shift because the AM system canot keep up with the input and the resultant high distortion causes a shift in average power Dynamic Range As mentioned previously with reference to Figure 3 29 the AM input is an ALC input which does not differ in its effect from a power entry input Therefore the AM system is limited by where it is operating within the ALC range In the normal coupled operating mode the ALC will likely be set between 10 dBm and 0 dBm see the preceeding pertinent section Depending on frequency the maximum available power is between 1 dBm HP 8340B and 21 dBm The ALC is reasonably accurate down to 20 dBm and typically is well behaved to about 30 dBm Expressing the desired modulation depth in dB s will let the user determine the range over which the ALC loop is being exercised Thirty percent AM creates excursions of 2 3 dB to 3 1 dB relative to the quiescent level 50 3 5 dB to 6 0 dB 90 5 6 dB to
151. tes that contain computer specific language specific information for those wishing to use another language contact the nearest HP Sales and Service Office listed inside of the back cover for a list of HP 8340B 41B Programming Notes HP IB COMMAND STATEMENTS Command statements form the nucleus of HP IB programming they are understood by all instru ments in the network and when combined with instrument specific codes they provide all manage ment and data communications instructions for the system An explanation of the fundamental command statements follows However some computers use a slightly different terminology or support an extended or enhanced version of these commands Con sider the following explanations as a starting point but for detailed information consult the BASIC language reference manual the I O programming guide and the HP IB manual for the particular computer being used Syntax drawings accompany each statement All items enclosed by a circle or oval computer specific terms that must be enterd exactly as described items enclosed in a rectangular box are names of parameters used in the statement and the arrows indicate a path that generates a valid combination of statement elements HP 8340B 41B Operating Information 3 53 3 54 Here are the eight fundamental command statements Abort Abort abruptly terminates all listener talker activity on the interface bus and prepares all instru
152. the MOD value The POWER dBm display shows actual power when the HP 8340B 41B is in CW or wide pulse pulse modulation modes this actual power changes very little as the pulse width is narrowed even though the POWER dBm reading drops Therefore at this point reduce the pulse width to the desired value and ignore the POWER dBm display The ATN and MOD values in the ENTRY DISPLAY also have a limitation Although the ATN displayed value is always accurate the MOD becomes saturated in the top 10 dB approximately of its range at which point no change occurs in the true power furthermore the modulation entry is only approximately calibrated Consequently rely on the POWER dBm display for the true power level instead of the MOD value See Figures 3 14 and 3 15 for additional pulse modulation information SHIFT METER can also be used as a diagnostic function for the ALC circuits as described in Section VIII Service Figure 3 16 Leveling Keys Input 2 of 2 Operating Information HP 8340B 41B RF Keys Output DESCRIPTION All RF power functions except for power level controlled by these keys and the RF output portis contained in this group PANEL LAYOUT ON OFF 5 9 KR PEAK PHR IF OUT PUT FUNCTIONS AMTD MKR HP IB AK1 turns on amplitude markers turns off amplitude markers on a CRT display When the markers are activated after an INSTR PRESET markers M1 M5 appear
153. the acceptors that data on the DIO lines must now be considered invalid Upon completion of this step one byte of data has been trans ferred T7 T 9 Source changes data the DIO lines T49 T42 Source delays to allow data to settle on the DIO lines Figure 3 26 Handshake Timing 1 of 2 Operating Information HP 8340B 41B upon sensing DAV high set NDAC low in preparation for the next cycle NDAC goes low as the first acceptor sets it low Tg First acceptor indicates that it is ready for the next data byte by setting NRFD high NRFD remains low due to other acceptors driving it low T4 Last acceptor indicates that it is ready for the next data by setting NRFD high NRFD signal line goes high Source upon sensing NRFD high sets DAV low to indicate that data on the DIO lines is settled and is valid First acceptor sets NRFD low to indicate that it is no longer ready then accepts the data First acceptor sets NDAC high to indicate that it has accepted the data T Last acceptor sets NDAC high to indicate that it has accepted the data as at Tig Source having sensed that NDAC is high sets DAV high as at T T 7 Source removes data byte from the DIO signal lines after setting DAV high Tag upon sensing DAV high set NDAC low in preparation for the next cycle All three handshake lines return to their initialized states as at T an
154. ther example 100 ENTER 719 USING z 1238 A suppresses EOL and indicates that string variable A is to be filled with 123 bytes of literal data 123A Note Be careful when using byte counting image specifiers because if the requested number of bytes does not match the actual number available data might be lost or the program might enter an endless wait state The suppression of the EOL sequence is frequently necessary to prevent a premature termination of the data input When not specified the typical EOL termination occurs when an ASCII LF line feed is received However the LF bit pattern could coincidentally occur randomly in a long string of binary data where it might cause a false termination Also the bit patterns for the ASCII CR carriage return comma or semicolon might cause a false termination Suppression of the EOL causes the computer to accept all bit patterns as data not commands and relies on the HP IB EOI end or identify line for correct end of data termination The various programming codes that are associated with the ENTER statement are listed in Tables 3 1 and 3 2 and are explained in the Programming Codes subsection Related statements used by some computers CONVERT IMAGE IOBUFFER ON TIMEOUT SET TIMEOUT TRANSFER This completes the HP IB Command Statements subsection The following material explains the HP 8340B 41B programming codes and shows how they are used with the OUTPUT and ENTER HP
155. these common generic terms for HP IB all are electrically equivalent although IEC 625 uses a unique connector This portion of the manual specifically describes interfacing the HP 8340B 41B to one very special type of instrument a computer INTERCONNECTIVE CABLING Figure 3 20 shows the HP 8340B 41B rear panel HP IB connector and suitable cables and describes the procedures and limitations for interconnecting instruments Cable length restrictions also described in Figure 3 20 must be observed to prevent transmission line propogation delays that might disrupt HP IB timing cycles INSTRUMENT ADDRESSES Each instrument in an HP IB network must have a unique address ranging in value from 00 30 decimal The default address for the HP 8340B 41B is 19 but this can be changed by the SHIFT LOCAL function as described in Figure 3 12 the examples in this section use 19 as the address for the HP 8340B 41B Other instruments use a variety of procedures for setting the address as described in their operating manuals but typically either a rear panel switch or a front panel code is used HP IB INSTRUMENTS NOMENCLATURE HP IB instruments are categorized as listeners talkers or controllers depending on their current function in the network Listener A listener is a device that is capable of receiving data or commands from other instruments Any number of instruments in the HP IB network can simultaneously be listene
156. tic functions always in the fundamental units of Hz dB m or seconds There are three diagnostic functions that can be used with OD 1 Oscillator frequencies diagnostic Programming code SHM1 keystrokes SHIFT M1 see figure 3 9 activates this diagnostic which outputs the M value N value M N loop frequency and the 20 30 loop frequency In BASIC 100 OUTPUT 719 SHM1 0 110 ENTER 719 M N R L 120 PRINT M VALUE M 130 PRINT N VALUE 140 PRINT M N FREQUENCY Hz 150 PRINT 20 30 LOUP FREQ L Hz 2 Band number YIG oscillator diagnostic Programming code SHM2 keystrokes SHIFT M2 see Figure 3 9 causes the band number and YIG oscillator frequency to be output in this order In BASIC 100 OUTPUT 719 SHM2 OD 110 ENTER 719 B Y 120 PRINT BAND NUMBER B 130 PRINT YIG OSC FREQUENCY Y Hz 3 Phase lock loop PLL frequencies diagnostic Programming code SHM3 keystrokes SHIFT M3 see Figure 3 9 causes the PLL 42 VCO frequency and the PLL 3 upcon verter frequency of the 20 30 loop to be output in this order In BASIC 100 OUTPUT 719 SHM3 OD 110 ENTER 719 F2 F3 120 PRINT PLL 2 F2 HZ 130 PRINT PLL 3 F3 HZ 4 Diagnostic Tests and Results Programming code SHM4 keystrokes SHIFT M4 see Figure 3 9 causes a series of up to 18 diagnostic tests These tests are labeled 14 to 31 Other tests are intiated at power on These tests are labeled 0 to 13 Te
157. tive Control Registers 3 96 3 4 START CW CF Frequency Display 3 15 Table Page 3 5 STOP AF Frequency Display 3 16 3 2 HP 8340B 41B Programming Codes 3 61 3 6 Entry Display 3 17 3 3 The Standard ASCII Code 3 89 3 7 Function Keys 3 19 3 8 KNOB STEP Entry 3 22 POWER CONTROL AND 3 9 Frequency Marker Keys 3 24 MODULATION INFORMATION 3 10 Entry Keys 3 26 x 3 11 Sweep and Trigger Keys sae iw ee 3 12 Instrument State Keys 3 31 Power dBm Display En 3 99 3 13 Power Switch Sweep Output 3 34 Decoupled Mode 3 100 3 14 Modulation Keys 3 35 UNLEVELED MODE 3 102 3 15 Modulation Input 3 36 POWER SEARCH 3 104 1 Leveling Keys INDUL tesa sus 9 97 EXTERNAL LEVELING 3 104 3 39 EXTERNAL SOURCE MODULE LEVELING 3 105 3 18 Rear Panel BNC Connectors 3 42 Detector Characteristics 3 105 3 19 Rear Panel RF Output 3 44 POWER dBm Display used with the 3 20 HP IB Connector 3 45 MCA Neue 3 107 3 21 0410 Interface Lg Bandwiditi eun Quo eds Ooh 3 107 9 22 HP 87550 Interface 3 49 AMPLITUDE MODULATION 3 108 3 23 Fan Assemb
158. tomated systems the displays of the HP 8340B 41B might be redundant and can be blanked to reduce visual distractions for the operation A BASIC example 100 OUTPUT 719 DUO If DU1 is output while the HP 8340B 41B is in the middle of a sweep the sweep will abruptly stop retrace and the resume sweep operations EK Enable Knob activates the rotary KNOB on an otherwise remote HP 8340B 41B front panel Once the KNOB is enabled it is automatically coupled to the presently active function such as 100 OUTPUT 719 KNOB adjusts CW frequency FP 200 OUTPUT 719 PLEK KNOB adjusts Power Level In the above examples the CW and PL function codes were output along with EK to explicitly specify the active function since no data accompanied the function codes the last used data values or the IP default values will be re established EK can also be output alone 300 OUTPUT 719 310 OUTPUT 719 CF70MZ 320 PAUSE 330 OUTPUT 719 DF 1MZ 340 PAUSE 350 OUTPUT 719 5 50 5 PL 25DB 360 PAUSE EK always controls the active function hence at line 320 the KNOB controls the center fre quency initially at 1 MHz and at line 340 the KNOB controls the delta frequency initially at 1 MHz and at line 360 the KNOB controls the power level initially at 25 dBm Notice at line 360 that the KNOB controls PL not ST because PL is the last activated function Fast Phaselock is used when th
159. tor but even with a perfect detector the external leveling circuitry is not as fast as internal It typically will level pulses wider than 2 usec HP 8340B 41B Operating Information 3 111 3 112 DETECTOR CIRCUITRY HIGH BAND DETECTOR 2 3 26 5GHz 83408 S H 2 3 28 Q8GHz HP 8341B LOG AMP SWITCH LOW BAND DETECTOR 01 2 3GHz Operating Information LOW BAND DETECTOR BANDWIDTH CONTROL CLOSED FOR FREQUENCIES 400MHz B PULSE WAVEFORMS 50nsec DIV S nSEC DIV Figure 3 34 Pulse Measuring System BUFFER TO POWER dBm DISPLAY AND TO ERROR DETECTION CIRCUITS FOR COMPRRISON WITH ALC INPUTS HP 8340B 41B Another type of leveling error arises from long pulse periods low repetition rates or more precisely long off times between pulses The problem lies in the error detection and modulator drive circuits shown in Figure 3 35 On the left is the comparison point where the ALC input is compared to the detector output For this discussion assume the two resistors are equal in value so if the ALC and detector voltages are equal in magnitude but opposite in polarity the error signal will be zero The error is fed to an integrator through the integrate hold switch This switch is closed continuously during CW operation Any error signal causes the integrator output to change at a controlled rate determined by capacitor C changing the RF output via the linear modu
160. tors and red warn ing annunciators REMOTE amber annunciator lights when the HP 8340B 41B is being remotely controlled by a com puter When REMOTE is lighted all front panel operations are disabled with three exceptions The POWER switch can only be locally operated the rotary KNOB can be enabled by using the EK programming code and the LOCAL key will override the computer and restore local control unless the computer sent a LOCAL LOCKOUT command to the HP 8340B 41B which disables the LOCAL key Figure 3 6 Entry Display 1 of 2 HP 8340B 41B Operating Information 3 17 FAULT amber annunciator lights when one of the internal circuits performs atypically To identify the affected circuit press SHIFT MANUAL which will cause FAULT CAL KICK ADC PEAK to appear in the ENTRY DISPLAY The flashing letters identify the faulty circuit as CAL calibration constants KICK YO or YTM kick pulses ADC analog to digital converter PEAK power peaking or TRK tracking control at this point the In Case of Difficulty section of this manual should be consulted for further instructions EXT REF amber annunciator lights when an external frequency source is used as the reference standard instead of the internal crystal oscillator The internal external frequency standard is selected by a rear panel switch see Figure 3 18 for an explanation of this switch and the associated connec tors OVERMOD red annunciator ligh
161. tput coupled parameters OD Output diagnostic values OF d Output fault values OI 19a Output identification OK d Output last lock frequency HP 8340B 41B Code OL 123b OM 8b OP d OR d OS 2b PLdt PMm 5 RB 1b RE1b RFm SHA3 dt SHAK SHAL SHAM m SHCF dt SHCW SHEF SHFA dt SHFB dt SHIP SHM1 SHM2 SHM3 SHM4 SHM5 SHMO SHMP SHPL dt SHPM SHPS dt SHRC SHS1m SHS 3 SHSL dt SHST dt i i Table 3 2 8340B 41B Programming Codes 2 of 4 Operation Performed Output learn data Output mode data Output interrogated parameter Output power level Output status bytes Power level Pulse modulation Power sweep Remote rotary knob Recall instrument state Extended status byte mask RF output on off Status byte mask RF peaking Reset sweep Sweep continuous Sweep single Sweep manual Seconds terminator Step frequency size Sweep single Shift prefix Disable ALC set power Enable external source module leveling mode Access linear modulator Immediate YTM peak Save current freq mult factor Pulse modulation enhancement Set frequency step size CW increment resolution Restore calibration constant access function Display multiplier Display offset Freq multiplier defaults to 1 Diagnostic M N 20 30 frequency Diagnostic band YO Diagnostic 1 VC02 frequencies Diagnostic test display results Tur
162. ts when excessive positive or negative voltage is applied to the front panel FM MODULATION INPUT or when excessive negative voltage is applied to the front panel AM MODULATION INPUT In the case of AM this excessive negative voltage causes the HP 8340B 41B to attempt to exceed the maximum modulation depth This happens at approximately 1 volt AM input Positive excursions have no limit as long as maximum available power is not exceeded at which point the UNLEVELED annunciator lights AM linearity will suffer for inputs above 4 1 volt As with the UNLEVELED annunciator an OVERMOD indication may signify an internal malfunction The OVERMOD condition can be caused by an FM input signal which significantly exceeds a Modulation Index peak deviation in MHz modulation in MHz of 5 amber annunciator lights when a remotely controlled HP 8340B 41B initiates a Service Request SRQ does not apply to local operation Several conditions can cause a Service Request including altered parameter values syntax error power failure and unleveled power The SRQ annunciator remains lighted until the computer sends an acknowledgement signal to the HP 8340B 41B Service Requests are more fully explained in the HP IB Programming part of this Operation chapter and in the In Case of Difficulty section OVEN red annunciator lights when the oven for the reference crystal oscillator is not at operating temperature A cold oven typically requires 5 30 minutes t
163. ttern could unintentionally occur in the middle of a data sequence To prevent a false termination the line is used to signify the true end of a data sequence alternatively a byte counting method that explicity defines the number of expected data bytes may be used THE TWELVE HP IB MESSAGES The HP IB control handshake and data lines interact to transfer information between interconnected instruments This information transfer process can be organized into 12 distinct categories which are by convention referred to as bus messages These messages will be explained using the following HP IB mnemonics Attention HP IB line TRUE indicating Command operating mode ATN Attention line FALSE indicating DATA transfer mode CA Controller active state CR Carriage Return ASCII decimal 13 data or more ASCII data bytes the HP 8340B 41B accepts lower case ASCII characters which it automatically upshifts DCL Device Clear returns all instruments addressed or not addressed to an instrument defined state DCL is accomplished by ASCII DC4 decimal 20 GET Group Execute Trigger initiates a simultaneous instrument defined response from all instru ments accomplished by ASCII BS decimal 8 GTL Go To Local returns instruments to local front panel control accomplished by ASCII SOH decimal 1 LA Listener active state LAD Listen Address of a specific Device see LAG LAG Listen Address Grou
164. ulse is detected by the crystal detector It trails the pulse input by 55 nsec representing propogation delays in the pulse modulator and its drive circuits The output of the crystal detector is amplified by a logarithmic amplifier log amp The log amp is used for several reasons one of which is its high gain for small signals reducing the effects of sample and hold errors Trace 3 is the output of the log amp The delay and relatively slow rise time are caused by the finite bandwidths of the detector and log amp The pedestal arrow represents the RF amplitude This level is captured for further processing by the sample and hold circuit S H represented by the switch capacitor combination Trace 4 shows the signal controlling the switch which is closed when trace 4 is high Trace 4 is timed to coincide with the pedestal of trace 3 This timing is done by circuitry associated with the pulse modulator and is factory adjusted for best coincidence Since the S H switch is closed only during trace 3 s pedestal the capacitor charges to a constant dc voltage This voltage is the same as what comes out of the log amp during CW operation at the same power level The capacitor is isolated by a buffer to prevent the following circuits from discharging it between pulses The output of the buffer is compared to the ALC inputs in the same manner as with CW operation Figure 3 34 shows a 200 nsec pulse If the pulse were narrowed to 100 nsec trace 3 woul
165. unctions including EXT TRIGGER INPUT MUTE OUTPUT PENLIFT OUTPUT NEG BLANK and Z AXIS BLANK MKRS There is also a pin unit input for a switch closure to execute the UP key function which is used to step through series of saved instrument states Additional information is contained in the HP 8410B C Operating and Service Manual Figure 3 21 HP 8410B C Interface Cable 1 of 2 HP 8340 41 Operating Information 3 47 HP 8410C INTERFACE CONNECTOR 218 J18 Signal J18W46 Mnemonic Levels Input Output Source A62J31 Pin Wire Pin Destination Color Code Z AXIS BLAND 5V 5V OUTPUT A57P1 99 a OUTPUT A57P1 59 10 24 A r U a lt ALTSEL TTL LOW TRUE TTL LOW TRUE I O A57P1 107 5 19 LSTOP SWEEP A52P1 17 18 41 42 3 UT m TTL LOW TRUE INPUT 57 1 61 8 22 0 EXT TRIG EXT SOURCE INPUT LEVEL INPUT OUTPUT A57P1 108 OUTPUT 57 1 41 1 15 OUTPUT A57P1 58 11 25 OUTPUT A57P1 60 9 23 STOP SWEEP BNC GND LUG INPUT A62J1 28 14 A57P1 106 4 18 6 a 1 PEN LIFT SEE TEXT N 14 NEG BLANK 5V 6 LRETRACE TTL LOW TRUE 17 r Q z ALTEN TTL LOW TRUE E 19 2 1 22 LSTEPUP TTL LOW TRUE co 24 8410 TRIG TTL LOW TRUE OU
166. used always 0 PWR SWEEP SLOPE RF not used not used OM 3 74 Operating Information 8340B 41B BYTE 8 shows the remaining front panel modes and functions with the True bits 71 indicating ON and the False bits 0 indicating OFF Bits Mode or Function not used always 0 not used always 0 not used always 1 PULSE not used AM PEAK Penlift enabled SHIFT LINE NOOR ODM OP d Output interrogated Parameter instructs the HP 8340B 41B to output the numerical value of any specified function even if that function is not presently active The code for any function that has a numerical value associated with it as appended to OP for example OPCF for the center frequency but not CFOP or OPST for the sweep time but not STOP The numerical value is always output in the fundamental units of Hz dB m or seconds A BASIC example 100 OUTPUT 719 OPCF 110 ENTER 719 120 PRINT CENTER FREQUENCY N HZ In this example N is an arbitrary variable OR d Output power level causes the HP 8340B 41B to output the present power level of the instru ment PLOA OPPL and OR can be used to output power level but there is a significant difference in the implementation of these codes by the HP 8340B 41B OR causes the power to be measured by the internal ADC while PLOA and OPPL reflect the user requested power that is shown in the ENTRY DISPLAY PLOA or OPPL accurately
167. value will appear in the ENTRY DISPLAY Use either the KNOB the STEP keys or the numerical keys with the dB m terminator keys to set any positive slope value between 0 000 to 1 500 dB GHz Press SLOPE again to cancel this function SLOPE functions in dB GHz units but SL the equivalent HP IB code functions in the fundamental units of dB Hz Therefore the SL code should be programmed as SLmdt where m is 0 off or 1 on d is the numerical value in dB Hz and t is either DB or the ASCII LF terminator For example to obtain a slope of 1 5 dB GHz use this procedure 1 1 5 dB GHz 1 5 dB 1 000 000 000 Hz 2 1 5 dB 1E9 Hz 1 5E 9 dB Hz 3 Programming code is then SL11 5E 9 DB SHIFT SLOPE HP IB SHSL allows front panel control of the mechanical attenuator ATN Press SHIFT SLOPE and ATN x dB where x is the last entered value will appear in the ENTRY DISPLAY Use the STEP keys or the numerical keys with any terminator key to change the attenuator value within the range 0 dB to 90 dB 10 dB steps Keyboard entries are automatically rounded to the nearest 10 dB The clicking sound heard after each attenuator change is the attenuator pad being mechanically switched into the RF output path Figure 3 17 RF Keys Output 2 of 3 3 40 Operating Information HP 8340B 41B RF HP IB RF1 turns RF output RFO turns off RF output turns the RF output on or off Press R
168. weep limits fall outside the frequency range of the HP 8340B 41B in that case the HP 8340B 41B will automati cally scale down the AF to be within the frequency range SHIFT MKR CF has no effect on the HP 8340B 41B Figure 3 9 Frequency Marker Keys 2 of 2 HP 8340B 41B Operating Information 3 25 DESCRIPTION This is the numerical keypad with the terminator keys that provides data entry to the HP 8340B 41B PANEL LAYOUT _ 9 6 9 amp FUNCTIONS 0 9 HP IB decimal numbers 0 through 9 minus sign and decimal point are the numer ical data entry keys Press any function key enter the desired numerical value then press the appro priate terminator key GHz sec dB m etc Table 1 1 Specifications lists the numerical limits for each function SHIFT data entry key has no effect on the HP 8340B 41B BACK SPACE is a minus sign entry when this key is pressed at the beginning of a data entry sequence a back space at all other times SHIFT BACK SPACE has no effect on the HP 8340B 41B GHz dB m MHz sec kHz msec Hz AUTO are the terminator keys that must be pressed after a numerical value has been entered The HP 8340B 41B interprets the terminator key to match the selected function For example GHz is selected when a frequency function is active dB m is selected when a power function is active An exp
169. weeps will of course be unleveled When in the unleveled mode there is no feedback stabilization of power and its stability versus time and temperature is unspec ified This mode is useful for signal tracing while troubleshooting the HP 8340B 41B It is also useful in some pulse modulation applications as explained in that section It can also be used to output in the presence of large reverse power a problem described under decoupled mode To do so the reverse power s effect on the POWER dBm display must be eliminated by shutting that power off or temporarily setting the HP 8340B 41B s attenuator to a high value Then in the unleveled mode SHIFT METER use the knob to set the desired ALC level via the power dBm display remember to mentally compensate for any attenuation in use Then remove attenuation or turn on the reverse power In the presence of reverse power the POWER dBm display will change to an incorrect value but the output power will be as previously set 3 102 Operating Information HP 8340B 41B
170. with performance limited by the dynamic range and leveling bandwidth of the individual source modules AMPLITUDE MODULATION The HP 8340B 41B provides linear dc coupled amplitude modulation when internally leveled or exter nally leveled with a square law detector or power meter The input resistance is 6000 whether the AM function is on or off The sensitivity is 100 per volt 5 This means that 1 0 volt doubles the output voltage 6 dB while 1 0 volt shuts the output completely off The input accepts 15 V dc with no damage and is resistor diode clamped to protect against higher voltage transients Most sine wave generators are calibrated in terms of RMS voltage so 0 707 V RMS equals 1 00 V peak The generator s output meter is accurate only if the load impedance equals the source impedance POWER dBm Display used with AM The POWER dBm display on the HP 8340B 41B always tells actual output power A dc input to the AM jack causes the power level to shift and the display reflects this 1 0 volt causes the display to increase 6 dB If that much power is not available the UNLEVELED annunciator lights and the display shows the actual output Inputs which reduce the ALC level below 22 dBm will blank the display Inputs of 1 0 volt or more negative shut off the output and light the OVERMOD annunciator The POWER dBm display is filtered so that it will not flicker for AM rates above 20 Hz The filtering creates an average of RF vol
171. ws the attenuator to be set remotely and is used when the attentuator is decoupled from the ALC SHSL initiates the decoupling The standard attenuator see the attenuator options listed in Section I has a range of 0 to 90 dB in 10 dB increments set the attentuator by using the code ATxDB where x is the numerical value the HP 8340B 41B will round values to the nearest 10 dB and DB is the terminator A BASIC example 100 OUTPUT 719 AT 40DB BC Band Change causes the HP 8340B 41B to advance to the next frequency bandcrossing point The BC code is used in two situations 1 It is used when the HP 8340B 41B is in network analyzer mode the NA programming code or 2 it is used when automatic bandcrossing has been disabled by the SHA21 code in this case the BC code functions identically to the SHA1 code bandcross disabling and the SHA1 SHA2 functions are described in Figure 3 16 CS Clear Status bytes resets to zero the 16 bits in the two status bytes Any status bit that is in the process of being set but was deferred pending completion of some function will also be cleared by CS Status bytes along with the CS code are explained under the OS Output Status byte code Operating Information HP 8340B 41B d ce 4 DUm Display Updating blanks DUO or unblanks DU1 the front panel displays of the HP 8340B 41B and is identical in function to SHS1m SHIFT CONT which is described in Figure 3 11 In au
172. y RB so the decimal value of Count has an allowable range of 127 to 128 The sampling time is arbitrary 75 milliseconds was selected for this example because the resultant response of the computer s knob approxi mates the response from the HP 8340B 41B s knob the exact effects of the sampling time must be ascertained by experiment REb RMb Request mask Extended and Request Mask allow masking of the extended status byte status byte 2 and the service request status byte status byte 1 respectively Masking is usually done for interrupt programming where non critical bits of the status bytes are masked to prevent them from initiating an unimportant interrupt To mask a status byte the HP 8340B 41B must receive the RE and or RM code that includes the numerical value of the enabled bits The numerical value of the bits in decimal is BIT T 6 5 4 3 2 1 0 DECIMAL 128 64 32 16 8 4 2 1 For example to enable bit 2 on status byte 1 while occluding the six other bits the programming code is RM amp CHR 4 where the decimal value of bit 2 is converted to binary by the CHR function and concatenated to the RM code Masked interrupt programming requires the identification and enabling of the computer s inter rupt register and the transmission of the RM RE codes to the HP 8340B 41B Here is a typical BASIC example 100 OUTPUT 719 CS 110 OUTPUT 719 RM amp CHR C4 120 OUTPUT 719 RE amp CHR C64 130 ENABLE INTR 7 8
173. y adjusts the manual sweep bandcrossing point for optimum results HP 8340B 41B Operating Information 3 79 SNdt Sweep Number is used to establish the number of steps for a stepped sweep The minimum number of steps is 10 while the maximum number is 1000 the frequency sweep span is divided by this SN number to determine the step increment SN initializes the stepped sweep conditions but the IF code or the HP IB statement TRIGGER must be used in conjunction with SN to actually initiate each frequency step A BASIC example 100 OUTPUT 719 FA8GZFB1262 SN400 110 FORN 1TO 400 120 OUTPUT 719 IF 130 NEXT N This program causes a sweep that starts at 8 GHz and makes 400 steps 19 MHz increments to the 12 GHz stop frequency The IF code in line 120 initiates each of the 400 increments natively line 120 could be 120 TRIGGER 719 SPdt Set Power step size is identical to the SHPL code and both are equivalent to the SHIFT POWER LEVEL key which is described in Figure 3 7 The power step size can be as small as 0 05 dB or as large as 50 00 dB Once set the power level can be incremented by the UP code or decremented by the DN code Here is a BASIC example of a 120 dB discrete power sweep at a 12 GHz CW frequency 100 OUTPUT 719 CW 12 62 110 OUTPUT 719 SP 0 05 DB 120 OUTPUT 719 PL 110 DB 130 FOR N 1 2400 140 OUTPUT 719 150 NEXT N 160 GOTO 120 The power sweep starts at 110
174. ystems which are not intended to deal with it especially demodulation systems HP 8340B 41B Operating Information 3 115 3 116 The HP 8340B 41B s high band gt 2 3 GHz employs a tracking YIG filter which essentially eliminates video feedthrough Attempts to measure it can turn out to be measurements of ground currents in coaxial cables The HP 8340B 41B s low band 2 3 GHz employs a low level mixer followed by a high gain amplifier At high power levels the bias levels in the amplifier shift slightly as the RF is turned on or off The slew of the bias from one level to another couples to the output and produces the video feedthrough waveform For this reason the 5 specification is only valid for power levels up to 8 dBm At low ALC levels 10 dBm another mechanism predominates Mixer imbalance produces dc at the output of the mixer and its magnitude varies with RF amplitude and or modulator state This shifting dc level couples through the amplifier which is AC coupled and emerges as video feedthrough spikes In percentage terms this mechanism gets worse at low levels The lowest per centage video feedthrough is probably found at ALC levels around 0 dBm RF ENVELOPE WITH VIDEO FEEDTHROUGH RF ENVELOPE VIDEO FEEDTHROUGH Figure 3 37 Video Feedthrough SLOW RISE TIME PULSE MODULATION FOR SCALAR NETWORK ANALYZERS For proper operation of HP 8755C 8756A and 8757A scalar analyzers the HP 8340B 41B offers a puls

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