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HP 8308A User's Manual

1. HP 8508A Vector Voltmeter User s Guide F e eyano gt ET Kt need N A n were na a ie HEWLETT PACKARD tut oe Contents Contents SECTION 1 GENERAL INFORMATION Introduction 1 1 Specifications 1 1 Safety Considerations 1 1 Instruments Covered by Manual 1 1 Description 1 2 Options 1 3 Mechanical Options 1 3 Instrument Options 1 4 Documentation Options 1 4 Support Option 1 4 Accessories Supplied 1 4 Equipment Available for use with the HP 8508A 1 4 Recommended Test Equipment 1 5 SECTION 2 INSTALLATION Introduction 2 1 Initial Inspection 2 1 Preparation for Use 2 2 Power Requirements 2 2 Line Voltage Selection and Fuse 2 2 Power Cable 2 3 Operating Environment 2 3 Mating Connectors 2 4 Rack Mounting 2 4 Hewlett Packard Interface Bus 2 5 HP IB Connector 2 5 HP IB Cables 2 6 HP IB Address Selection 2 6 Storage and Shipment 2 8 Environment 2 8 Packaging 2 8 SECTION 3 OPERATION Getting Started 3 1 Introduction 3 1 Operator s Maintenance 3 1 New User Introduction 3 2 Front Panel Features 3 4 Measurement Keys 3 4 Function Keys 3 5 Instrument State 3 6 Display Area Keys 3 6 Rear Panel Features 3 8 E1089 Contents Making Measurements Basic Measurements Introduction Getting Acquainted with the Vector Voltmeter Measurements with probes What you have achieved Advanced Measurements Measurements in a 50 ohm system Typical Configuratio
2. As the HP Model 8508A mainframe cannot be performance tested without a Probe Module installed the full per formance test information is contained in Section 4 of the Input Module insert Performance Tests Lo 1 tb Adjustments Adjustments Section 5 5 1 INTRODUCTION This section describes the adjustment procedures required to enable the Hewlett Packard 8508A Vector Voltmeter to meet the specifications listed in Table 1 2 of the Probe Input Module manual Adjustments should only be made after determining that the instrument is out of calibration or if a repair has been carried out 5 2 WARM UP TIME The HP 8508A must be switched on for a minimum of 30 minutes before carrying out any adjustments This allows the instrument operating temperature to stabilize 5 3 SAFETY CONSIDERATIONS WARNING PROCEDURES DESCRIBED IN THIS SECTION ARE PER _ FORMED WITH THE PROTECTIVE COVERS REMOVED AND POWER SUPPLIED TO THE INSTRUMENT SERVIC ING SHOULD ONLY BE PERFORMED BY TRAINED PER SONNEL WHO ARE AWARE OF THE HAZARDS INVOLVED Anti Static Precautions The printed circuit boards contained in this instrument have components and devices which are susceptible to damage by electrostatic discharge ESD To minimize the risks of damaging or decreasing the reliability of the instrument the following procedures and cautions should be observed when servicing the instrument Static free Workstation All servicing should be carried out
3. HP 10216A DC Block HP 5060 0549 Spanner Top Assembly 3 22 E1089 Operation ransmission measurements in 50 ohms Prebe inputs HP8508A Source geod Termination Probe Tee CAL Probe Tes Figure 3 18 Transmission Measurements Setup Equipment HP 8656B Synthesized Signal Generator HP 8508A Vector Voltmeter HP 11570A Accessory Kit includes 2 HP 11536A Probe Tee and 1 HP 908A Tonma HP 11851B Cable Kit 1 cable required in this setup or HP 11500B RF Cable Adapter from type N to DUT if required E1089 hammers n Operation Transmission measurements in 50 ohms Direct inputs Source Power Splitter Figure 3 19 Transmission Measurements Setup Equipment HP 8656B Synthesized Signal Generator HP 8508A opt 050 Vector Voltmeter with 50 ohm Input Module HP 11851B Cable Kit 3 cables required in this setup HP 11549A Power Splitter de to 1GHz or HP 11667A Power Splitter de to gt 2GHz Adapter from type N to DUT if required HP85084 E1089 Operation Reflection measurements in 50 ohms Probe inputs dual directional coupler HPe5084 Termination Probe Tee Source Dual Directional Coupler CAL i Figure 3 20 Reflection Measurements Setup Equipment HP 8656B Synthesized Signal Generator HP 8508A Vector Voltmeter HP 11570A Accessory Kit includes 2 HP 11536A Probe Tee and 1 HP 908A Termination HP 908A Termination total of 2 required HP 77xD Dual
4. 2 Select METER SELECT DISP2 to activate the meter on the B voltage then tune the source frequency for a maximum to set the source in the filter passband Tuning is achieved using the trend indicators LED s An increasing level is highlighted by the top LED being illuminated A decreasing level is highlighted by the bottom LED being illuminated A null is indicated by both LEDs being extinguished noogvooce Figure 3 10 Meter Display 3 Press B A MAG to measure the amplitude ratio and select DISPLAY dB to display a log ratio 4 Press SHIFT then SAVE REF to store the current reading zero the magnitude reading and refer future measurements to the filter passband 3 15 Operation 5 Now increase the source frequency until the display reads 3dB Note the source frequency This is the filter 3dB cutoff frequency a Transmission One good use of a CW receiver such as the HP 8508A is in the measurement of gain as a function of input level The HP 3508A automatically displays B A as a ratio so effects caused by changing input level can be seen directly To illustrate this we ll measure the 1dB gain compression point of a S0MHz 14dB gain amplifier Since the output at gain compression is specified to be 10dBm we ll use an HP 8491A 10dB attenuator at the output of the amplifier to minimize measurement errors due to high signal levels Source MPBSOSA 50 ohm 50 ohm A Input B input Power Split
5. Condition Registe Transition Filter Selects which transitions of Condition bits will set corresponding Event bits Event Register Latched Conditions _ Logical OR BEE f Event Enable Register SUM MARY ri n 1 Y 2 1 O Selects which events can set ihe Summary Message MESSAGE Figure 3 26 Register Model for the Status Data Structure The instrument also provides a Standard Event Status Enable Register and an Operation Status Enable Register and provides further commands toread them These registers work in the same way as the Service Request Enable Register described earlier in Sending the Status Byte Message E1089 3 37 Operation Standard Event Status Register SESR Figure 3 25 shows the operation of the Standard Event Status Register This is a specific application of the event registers discussed previously and its bit definitions are as follows Bit 5 Command Error CME This bit indicates that the device has detected a command error The following events cause a command error 1 An IEEE 488 2 syntax error This means that the device received a message which did not follow the syntax defined by the TEEE488 2 standard For example it received data which violated the device listening format 2 A semantic error occurred For example the device received an incorrectly spelled command Another example would be that the device received an optional TEEE488 2 command whi
6. Directional Coupler See Related Products section for frequency ranges HP 11851B Cable Kit 1 cable required in this setup or HP 11500B RF Cable Adapter from type N to DUT if required Calibration Standard Same as DUT connector 21089 Operation Reflection measurements in 50 ohms Direct inputs reflection bridge HP8508A Source nn 4 Reflected 4 insident CAL A RF input _ Transmission Reflection Test Set Figure 3 21 Reflection Measurements Setup Equipment HP 8656B Synthesized Signal Generator HP 8508A opt 050 Vector Voltmeter with 50 ohm Input Module HP 85044A Transmission Reflection Test Set HP 11851B Cable Kit 3 cables required in this setup Adapters from type N to DUT if required Calibration Standard Same as DUT connector p bs in Operation 3 11 REMOTE OPERATION THE HEWLETT PACKARD INTERFACE BUS The Vector Voltmeter is capable of remote operation via the Hewlett Packard Interface Bus HP IB which is Hewlett Packard s implementation of IEEE Standard 488 1 This section gives details of remote operation includ ing capabilities addressing input and output formats status and service requests All front panel functions except the LINE switch are programmable via HP IB In addition there are HP IB commands offering capabilities under remote control which are not available from the front panel keyboard The HP IB commands used in the Vector Voltmeter conf
7. IB ADDRESS SELECTION The HP IB address is selected via the front panel Press SHIFT VIEW ADDRESS and use the arrow Keys to scroll to the desired number Installation Be Table 2 5 HP IB Address Codes Address Characters SP gt I M oe HD BH me TOMMOO gt weer oo fo Zn H Lb WW HN Di F D Sum N XE lt C AYAOVOZECR 0 0 3 hin yY A e 2 7 ze Installation 2 14 STORAGE AND SHIPMENT Environment The instrument may be stored or shipped in environments within the following limits Temperature 40 Centigrade to 75 Centigrade Humidity up to 90 at 65 Centigrade Altitude 15300m 50000ft The instrument should also be protected from temperature extremes which may cause condensation inside it Packaging Tagging for Service If the instrument is being returned to Hewlett Packard for service please complete one of the blue repair tags located at the front of this manual and attach it to the instrument Original Packaging Containers and material identical to those used in the factory packing are available through Hewlett Packard offices If the instrument is being returned to Hewlett Packard for servicing attach a tag indicating the type of service required model number and full serial number Also mark the container FRAGILE to ensure careful handling Other Packaging The following general instructions should be used for re packaging with commercially available materials
8. MEAS to put the instrument into the ae mode The Display will now indicate which setup code 1s being used It wil l appear as tSt monn tSt indicates that the instrument is in the setup mode and anan is the current setup code Use the UP DOWN Arrow keys to set up test code 5 in Display 2 Press HOLD VALUE and check that the indicator lamp is iluminated 4 Remove the HP 8508A top cover to allow access to the adjustments 5 Configure the equipment as shown in the Figure 5 3 In this test a 100m V signal from the AC Calibrator is applied simultaneously to the Channel A and Channel B Input Amplifiers on the IF board A pair of miniature probe clips should be used to apply this signal between A3C1 and A3R150 for Channel A and between A3C21 and A3R170 for Channel B The location of these points is shown in Figure 5 4 E1089 5 9 Adjustments a i 47 17 af pa amp PROBE HERE PENNU me AM TR 4 i ha ur y Test Point Locations Figure 5 4 IF Measurement Assembl Cos rt Fl Adjustments Alternatively install the input module extender HP part number 08508 60032 in the HP 8508A Vector Voltmeter The input module is not required Set switch S1 on the input module extender to CALIBRATION and set switch S2 to EXTENDER CALIBRATION The 100mV signal from the AC Calibrator can be applied to either of the BNC connectors on the input module extender front panel 6 Set up the A
9. REF 1 PRESET Before beginning a new measurement press PRESET to return the HP 8508A to a known state The following list shows the preset condition MEASUREMENTS FUNCTIONS MEASUREMENTS A a aaan ON Er EEEE OFF DISPLAY Toe aeon oa UNITS FORMAT 2 a ee ea OFF 1320 1 6 ate on os OFF DISPLAYS REF SELECT ao OFF METER SELECT OFF POWER MEAS www we ee OFF LOCK RANGE a ae AUTO SYSTEM IMPD 0 OFF MAG RANGE AUTO HOLD VALUE nee OFF DISPLAY T asen mV DISPLAY ag blank 2 UNLOCKED INDICATOR Check that there is no input to the probes With no input signal the A UNLOCKED indicator should be ON and DISPLAY 1 the left display should indicate under range NOTE If there are high level radiated signals present DISPLAY 1 may give a reading This reading is caused by the un terminated probe acting as an antenna It will not affect the instrument s ee to make measurements on your circuit ze 7 3 SINGLE CHANNEL MEASUREMENT CHANNEL A The A probe is used as a reference by the HP 8508A and must be connected for the instrument to function The signal level should be in the range 300uV to IV Connect the A probe to the source and turn on the output The A UNLOCKED indicator should go OFF and DISPLAY 1 should show the source output voltage 4 VOLTAGE UNITS Select DISPLAY dB to have the HP 8508A compute and display the voltage in dBuV 5 POWER MEASUREMENT Press POWER MEAS to display power i
10. and read with the Enable Status ESE query 3 38 E1089 Operation DESICKED FOR SYSTEMS Register Bit Coding The Status Byte SESR Operation Status Register and Transition Filters are set using a value which determines the conditions to be enabled The weights of each of the bits to be enabled are summed to obtain the value required Table 3 1 shows the weighting of each bit for each of the registers Table 3 1 Register Bit Coding Bit f 2 4 3 2 0 Weight 128 64 32 16 8 4 2 1 HP IB Response Formats Results returned by the HP 8508A from measurement queries take the ASCH form lt gt 1 1 lt gt D DDDE lt gt lt gt DD lt term gt That is a leading sign a four digit mantissa between 1 000 and 9 999 an exponent designator E or e an exponent sign a two digit exponent between 00 and 99 and a terminator The value is always in fundamental units voits ohms watts dB etc The terminator lt term gt depends on the data requested as follows lt term gt is a comma where another data item follows as part of the same result lt term gt is a semicolon where the data item completes a result and another result follows lt term gt is linefeed lt lf gt with EOI set true where the data item is the last or only part of a result Using the SYSTem FORMat command results can also be coded as 64 bit Floating Point numbers in IEEE488 2 Definite Length Arbitrary Block Response Data format T
11. bytes It can be cleared by the Reset Command the Device Clear Command IEEE488 1 or by power on The Vector Voltmeter also has an Error Queue which operates as a FIFO and stores error messages until they are read from the Vector Voltmeter The Error Queue is summarised in the error bits bits 2 to 5 inclusive of the Standard Event Status Register It is read by the SYSTem ERRor command and can be cleared by using the Clear Status command CLS When the Error Queue is empty the string 0 NO ERROR is returned Event Registers Event Registers capture changes which occur within a device Each bit in an event register corresponds to some device condition Bits become TRUE when some pre defined device condition transition occurs The event register bits are latched so that once they become TRUE they cannot be cleared except by the user There are two means of clearing an event register Reading a register will clear it and the Clear Status command CLS will clear all event registers The Vector Voltmeter uses two kinds of transition filter for setting these event bits TRUE 1 Positive Transition The event becomes TRUE when its condition makes a FALSE to TRUE transition 2 Negative Transition The event becomes TRUE when its condition makes a TRUE to FALSE transition 3 30 E1089 Operation See Figure 3 26 for a detailed representation of the register model for the status data structure Device Status Continuously Monitored
12. commands and status information In general the query options return the recommended form of the corresponding command This is either a number where the command sets a range or sends data or sets the function ON or OFF or a string where the command itself is a string Status functions return a number to be decoded to determine conditions which have set status bits Service Requests HP IB devices may request service from the controller by asserting the SRO bus control line The controller usually responds to this signal by asking each device on the bus in turn for its Status Byte If bit 6 is set it indicates that the device requires service and the controller looks at the remaining bits in the Status Byte for further informa tion The interpretation of these bits depends on whether the device complies only with IEEE488 1 or like the Vector Voltmeter with TEEE488 1 and TEEE488 2 Bit 6 has two distinct functions Within IEEE488 1 it is the Request Service RQS bit and within IEEE488 2 is the Master Summary Status MSS bit IEEE488 2 also defines bit 5 as the Event Summary Bit ESB and bit 4 as the Message Available Bit MAV When dealing with service requests a key operational difference emerges between instruments which comply only with TEEE488 1 and those which meet TEEE488 2 as well If the Status Byte of a IEEE488 1 instrument is read by a Serial Poll Enable bus command the ROS bit is cleared as a consequence of the read operati
13. ee eee E A Wal a siala2i a Sparcard Event 78 5 21 0 Stats Register gt i i SR Bol eg E E A i i EIERN 2 H 4 AF L 1 AA E i i 1 H 3 H i A hn H i i DN ee ERE A E A i i R 4 8 8 Eek IE BE u i zlota g Standard Event Status Enable Register i pen ahs Queue i Not Eruty wtput Gueuse i mead by Seria Peil Service Request Status Bit Register Genara t ion resd by 375 Service Request Enaple Register SRE NRP SRE Figure 3 25 Standard Status Model E1089 Operation Queues Queues permit a device to report status or other information in a sequential manner Each queue has a summary message bit which indicates that the queue contains some information This bit will be TRUE when the queue contains any information otherwise it will be FALSE Reading a queue will remove a piece of information from it and a queue is considered empty when it no longer contains any information Queues can be cleared by reading all the information in them The Output Queue There are two queues in the status reporting structure of the Vector Voltmeter The Output Queue is a first in first out FIFO queue It stores output messages until they are read from the instrument The availability of data is summarized in the MAV bit of the Status Byte The Output Queue is read by addressing the instrument to talk and then handshaking the
14. mainframe the HP 8508A will display the error message Err 601 This reading should be ignored 3 Remove the HP 8508A top cover to allow access to the adjustments 4 Set A3R151 fully counter clockwise 5 Select PRESET SHIFT POWER MEAS to put the instrument into the setup mode The Display will now indicate which setup code is being used It will appear as St nnnn tSt indicates that the instrument is in the setup mode and nanan is the current setup code Use the UP DOWN Arrow keys to set up test code 4 in Display 2 Press HOLD VALUE and check that the indicator lamp is illuminated 6 Adjust A3R151 to obtain a zero reading in Display 2 7 Press HOLD VALUE to cancel the function 8 Replace the HP 8508A top cover A QO E1089 Adjustments Set up the amplitude path gain using an external 20kHz 100 mV reference source DESCRIPTION To ensure interchangeability of Input Modules the 100 mV level at the module interface must be accurately set AC Calibrator Figure 5 3 Reference Level Adjustment Equipment Setup EQUIPMENT Instrument Recommended Model AC Calibrator Datron 4200A PROCEDURE 1 Remove the Input Module from the instrument 2 Switch on the equipment and allow to warm up for 30 minutes Note Since the Input Module is not installed in the mainframe the HP 8508A will display the error message Err 601 This reading should be ignored 3 Select PRESET SHIFT POWER
15. office If the shipping container is damaged or the cushioning material shows signs of stress notify the carrier as well as the Hewlett Packard office Keep the shipping material for the carrier s inspection The Hewlett Packard office will arrange for repair or replacement at Hewlett Packard s option without waiting for a claims settlement providing that Hewlett Packard and or the carrier are notified within 12 days of shipment E1089 Installation 2 3 PREPARATION FOR USE WARNING TO AVOID THE POSSIBILITY OF INJURY OR DEATH THE FOLLOWING PRECAUTIONS MUST BE FOLLOWED BEFORE THE INSTRUMENT IS SWITCHED ON A NOTE THAT THE PROTECTION PROVIDED BY GROUNDING THE INSTRUMENT CABINET MAY BE LOST IF ANY POWER CABLE OTHER THAN THE THREE PRONGED TYPE SUPPLIED IS USED TO COUPLE THE AC LINE VOLTAGE TO THE INSTRUMENT B If THIS INSTRUMENT IS TO BE ENERGIZED VIA AN AUTO TRANSFORMER TO REDUCE OR INCREASE THE LINE VOLTAGE MAKE SURE THAT THE COMMON TERMINAL IS CONNECTED TO THE NEUTRAL POLE OF THE POWER SOURCE C THE POWER CABLE PLUG SHALL ONLY BE INSERTED INTO A SOCKET OUTLET PROVIDED WITH A PROTECTIVE EARTH CONTACT THE PROTECTIVE ACTION MUST NOT BE NEGATED BY THE USE OF AN EXTENSION CORD WITHOUT A PROTECTIVE CONDUCTOR GROUNDING 2 4 POWER REQUIREMENTS The instrument requires a power source of 100 120 220 240V AC 10 48 to 440Hz single phase The maximum power consumption is typically 40VA 2 5 LINE VOLTAGE SELECTION AND FUSE The line volta
16. operate similarly One press lights the LED and the measurement result is shown in the appropriate display window A second press turns off the LED and the measurement result Any single measure ment is available and any combination can be chosen by selecting the required measurements Note that A B A mag and B B A phase combinations can be selected using shifted functions that is pressing SHIFT and the appropriate key Ifa new measurement is selected which uses the same display as an existing measurement the existing measurement will be turned off for example selecting Phase when B is displayed will turn B off A Measures the amplitude of A Default is mV on Display 1 changeable to dBuV by toggling the DISPLAY key to dB Power can be displayed by pressing the POWER MEAS key and selecting either 50 or 75 ohms with the SYSTEM IMPD key Units available are uW and dBm B Operates in the same way as A but the value appears on Display 2 units are controlled by the DISPLAY key B A mag Measures the B A ratio Default is linear units on Display 1 changeable to dB using the DISPLAY key B A phase Measures the phase of B with respect to A in degrees Operation A B A mag Places the A measurement in Display 1 and the B A measurement in Display 2 B B A phase Places the B measurement in Display 1 and the B A phase in Display 2 DISPLAY Defines the scale associated with the display s depending on what measurement i
17. the A or B voltage depending on which is selected on the front panel and the phase difference No processing is carried out nor are any results available over HP IB The mode is intended for use in applications such as narrowband swept testing of crystal filters The default is OFF The query option returns 1 or 0 E1089 3 43 Operation Display State lt HPIB gt DISPlay STATe ONJOFF T IG Controls the front panel display The display can be turned off when not needed A speed improvement may be realized by switching the display off The improvement will be greater as AVERAGE COUNT is reduced since updating the le is an overhead at the end of the measurement cycle The default is ON The query option returns 1 or Q Fetch Results lt HP1B gt FETCH Continuous readings CONT i nuous This query returns the result of the measurement most recently started as soon as it is available The result will be generated using the current measurement configuration PETCh CONTinuous causes results to be passed to the HP IB such that when one is read the next is made available for reading as soon as it is calculated Format FORNat LiNear LOGarithmic POLar RECTangular CARTesian The format command sets the units in which measurement results will be returned LiNear Sets voltage and power units to volts and watts respectively and magnitude ratio to a dimensionless quantity LOGarithmic Sets voltage and power units to dBu
18. time Local and Remote Operation The Vector Voltmeter can operate under either local or remote control In local mode all front panel controls are operational and control the instrument In remote mode all front panel controls are inoperative except LCL when not in Local Lockout the instrument being controlled by the HP IB controller The front panel display reflects the remote programming commands received unless the display is switched off At power on the instrument assumes the local state Under local control all HP IB instrument commands will be ignored To gain control over HP IB the controller must put the instrument into the remote state This is accom plished by setting the Remote Enable REN bus control line true and sending the Vector Voltmeter s HP IB Listen Address In local mode the Vector Voltmeter s front panel controls are fully operational and it will respond to the Remote message Whether it is addressed or not it will also respond to the Clear Local Lockout and Clear Lockout Local messages When addressed to talk the Vector Voltmeter can issue Data messages and the Status Byte message Whether addressed or not it can issue the Service Request message E1089 3 97 Operation Local Lockout Local lockout disables the LCL key and allows return to local only under program control Local Lockout is recommended for purely automatic applications Remote to Local The instrument switches to local whenever
19. use the up down arrow keys to select band 20 0 02 0 02MHz Now press SHIFT SAVE REF to store the measure ment as a reference and normalize readings to the saved reference value 4 Insert the device to be tested between the RF source and the detector 3 20 E1089 Operation 5 Convert the modulation envelope phase change which is shown on Display 2 to delay using the following formula d phase t d _o hase f m x 360deg where t d delay in seconds d phase envelope phase shift m degrees f m modulation frequency in Hz In this case the modulation source is 20kHz Substituting this in the formula gives d phase d Le 72E 6 E1089 rat ica Operation 3 10 TYPICAL CONFIGURATIONS Probing measurements with external source HPBSOBA Source ya ef Probe Tee LAA Tre eae p pe oy pa a a a oor h rar G wee HA F H a a ee a eee y 2 1 t 1 a 1 i i a 1 i 2 i a i gt i gt i j 4 a mud fs Ciroult Under Test Figure 3 17 Probing Measurements Setup Equipment HP 8656B Synthesized Signal Generator HP 85084 Vector Voltmeter HP 11536A Probe Tee Part of HP 11570A Accessory Kit HP 118518 Cable Kit 1 cable required in this setup or HP 11500B RF Cable Adapter from type N to circuit under test if required Probe Accessories if required HP 11576A 10 1 Divider
20. 1 Z measurements absolute values can be displayed by choosing the appropriate SYSTEM IMPD of 50 or 75 ohms If values normalized to ZO are required choose NORM POWER MEAS Works with A and B amplitude only to convert the measured voltage to an equivalent power using the value selected by the SYSTEM IMPD key E1089 un LA Operation FORMAT The default display configuration for magnitude and phase related measurements is magnitude in Display 1 and phase in Display 2 An alternative real and imaginary format is available when displaying the following B A and Phase together rho and phase angle Z and 1 Z DELAY Uses the B A phase to make simple delay measurements The delay is calculated assuming a 4kHz change between the two frequencies The delay is shown in Display 1 with Display 2 showing dely for delay The delay can be zeroed by pressing SAVE REF INSTRUMENT STATE PRESET This key forces the instrument into a defined measurement state as follows A is displayed in mV with no other functions engaged and all ranging is automatic Error numbers showing in the display after self test routine indicate possible instrument failure Press PRESET again If the error number remains refer to the Service section information NOTE Err 601 indicates that the Input Module is not correctly installed LOCAL Returns the instrument to front panel control unless local lockout has been asserted over the HP IB ADDR
21. 1000mV for an input of 31 6mV The OUTPUT 2 sensitivity is fixed at 1mV per 0 1 degrees A typical use of this mode might be to make narrowband swept measurements on crystals Lad Co E1089 Operation 3 7 MAKING MEASUREMENTS 3 8 BASIC MEASUREMENTS Introduction There are two types of Input Module that can be used with the HP 8508A Vector Voltmeter mainframe These Input Modules are the HP 85081 High Impedance Input Module and the HP 85082 50 ohm Input Module The HP 85081 High Impedance Input Module has a frequency range from 100kHz to 1GHz This Input Module has high impedance probes which can be used either alone or with accessories to make in circuit measurements The following accessories are available HP 11570A Accessory Kit 50 ohm accessories HP 10216A Isolator probing accessory HP 115776A 10 1 Divider probing accessory The HP 85082 50 ohm Input Module has a frequency range from 300kHz to 2GHz This Input Module has 50 ohm type N connectors Using the HP 85082 gives you a higher frequency range than the HP 85081 for measurements in a 50 ohm environment Getting acquainted with the Vector Voltmeter To introduce you to the main functions of the HP 8508A here are a few simple measurements you can try You will learn to make single channel voltage and power measurements and measure the vector ratio between two voltages a Measurements with probes For this section measurements are made on a printed circuit board b
22. AND command is received The query option returns 1 or 0 Identification lt HP IB gt IDN The identification command returns a string which describes the Vector Voltmeter and Input Module The string contains four fields separated by commas as shown below HEWLETT PACKARD 8508A 050 0 REV 2944 AM E E ee e eem Manufacturer Firmware revision Model number Not used Input module option STD or 050 E1089 Operation Input iMPedance lt nrf gt POD iNPut Input impedance sets the impedance of the measurement system used in power and impedance measurements Allowed values are 50 or 75 Ohms The query option returns the current setting POD either 50 75 or HI Measure Timeout MEASure lt meas gt lt meas gt TIMEout lt nrf gt STATe ON OFF 1 0 This command is used to configure and make a Vector Voltmeter measurement or measurements and return the result s Default is AVOLtage Options for lt meas gt are listed below AVOLtage BYOL tage APGWer BPOWer BA PHASE TRANsmission DELay SWR RHO CORE Channel A Voltage using current setting of FORMat LOG LIN Channel B Voltage using current setting of FORMat LOG LIN Channel A Power using current settings of INPut iMPedance and FORMat LOG LIND Channel B Power using current settings of INPut IMPedance and FORMat LOG LIN B A Magnitude Ratio using current setting of FORMat LO
23. Assembly Replaced Perform the following Adjustments A1 Front Panel None A2 Power Supply 3 8 A3 IF Assembly 5 9 A4 Search amp Lock 5 10 AS Processor None 5 7 ADJUSTABLE COMPONENTS Table 5 3 lists all adjustable components in the HP 8508A Vector Voltmeter Reference Designation AZRI A2 R 16 A2 R19 A3L1 A3L2 A3 R151 A3 R178 A4 R89 A4L3 E1089 Table 5 3 Adjustable Components Adjustment Adjustment Description Name Paragraph 50V 5 8 Adjusts the 5 0Y REG Supply 12 0 V 5 8 Adjusts the 12 0V REG Supply 12 0 Y 5 8 Adjusts the 12 0V REG Supply Set 20 kHz Ch A 5 9 Sets centre frequency of bandpass filter Set 20 kHz Ch B 5 9 Sets centre frequency of bandpass filter Differential Phase 5 9 Sets 180 phase range on A3 100 mV Ref 5 9 Absolute gain adjustment Set 1 62 MHz 5 10 RC VCO centre frequency et 32 4 MHz 5 10 LC VCO centre frequency 3 3 Adjustments 5 8 POWER SUPPLY ADJUSTMENTS 12 0V 12 0V and 5 0V DESCRIPTION The 12 0V 12 0V and 5 0V power supplies are adjusted under load for the proper voltage levels with an Input Module installed EQUIPMENT Instrument Recommended Model Input Module HP 35081A or HP 85082A Digital Voltmeter DVM HP 3456A PROCEDURE 1 Install an Input Module in the HP 8508A mainframe 2 Switch on the equipment and allow to warm up for 30 minutes NOTE If an Error Code in the 200 Series ts displayed the power supply voltages sh
24. B A Phase Use Aas FCP ect CIO IRA ERA Phase Ref A Figure 1 1 Vector Signals The measurements are either of a single channel or the ratio between the two channels and results displayed as voltage or power in linear or log units normalized magnitude and phase angle or real and imaginary components In addition the HP 8508A has built in procedures for simple network analysis The HP 8508A has two configura tions the first providing two high impedance probe inputs with a frequency range from 100kHz to 1GHz and the second providing two 50 ohm type N connector inputs with a frequency range of 300kHz to 2GHz The configura tion can be changed by replacing the instrument s input module The HP 8508A can be used in applications where vector signal information is required at low cost particularly i in the design manufacture or service of RF assemblies The HP 8508A is a simple high sensitivity receiver and can be used with any source including one that is part of the device to be tested Its built in HP IB interface for program ming allows it to be used as an economical tool in automated production environments Typical measurements include voltage power gain or loss impedance and phase matching Measurements can be made either from the input to the output of the device or by probing within the device Other measurements include transmission and reflection procedures that include test system calibration against known standar
25. C Cabbrator for an output frequency of 20 kHz and a level of 100 mV 7 Adjust A3R178 to give a display reading of 100 0 0 1 on Display 2 8 Press HOLD VALUE to cancel the function 9 Remove the test chips and replace the HP 8508A top cover E1089 Adjustments 5 10 SEARCH LOCK ASSEMBLY ADJUSTMENTS Set up the centre frequency of the 1 62 MHz and 32 4MHz Oscillators DESCRIPTION The centre frequencies are set up using an internal test routine EQUIPMENT No external test equipment is required for this adjustment PROCEDURE 1 Remove the Input Module from the instrument 2 Switch on the equipment and allow to warm up for 30 minutes Note Since the Input Module is not installed in the mainframe the HP 8508A will display the error message Err 601 This reading should be ignored 3 Remove the HP 8508A top cover to allow access to the adjustments 4 Select PRESET SHIFT POWER MEAS to put the instrument into the setup mode The Display will now indicate which setup cede is being used It will appear as tSt nnan tSt indicates that the instrument is in the setup mode and nnnn is the current setup code Use the UP DOWN Arrow keys to set up test code 0 in Display 2 Press HOLD VALUE and check that the indicator LED is ON 5 Adjust A4R89 slowly until the UNLOCK light extinguishes Note The green LED CR6 across the board from A4R89 is functionally the same as the UNLOCK light on the fro
26. ESS Used to show the current HP IB address of the instrument It is changed by using the STEP keys The display reverts to measurement display when another key is pressed DISPLAY AREA KEYS MAG RANGE When MNL is selected the display resolution is controllable using the STEP keys which move the position of the decimal point When A and B are displayed together both displays show the same resolution DIR ANLG OUT When this mode is engaged the raw phase and magnitude detector outputs are fed directly to the rear panel so that external measurements can be made when a CW or swept source is used Internal gain ranging is forced into manual operation with the display showing XXX mV full scale deflection adjustable by use of the STEP keys The LOCK RANGE is also forced into manual mode The only valid measurement selection is A or B The HP 8508A will lose lock if the sweep rate exceeds approximately 1SMHz second or if the frequency reaches a lock range boundary LOCK RANGE When MNL is selected the instrument is prevented from signal searching outside the current frequency range RANGE Display the current lock range the range can then be changed by using the STEP keys The display reverts to measurement display when another key is pressed 3 6 E1089 Operation HOLD VALUE This retains the displayed values when the signal voltage crosses a fixed threshold or if the instrument loses lock If both displays are acti
27. GILINK B A Phase B A Magnitude Ratio and 8 A Phase computed from the same measurement using current settings of FORMAT LOGILIN and POL RECT Delay Standing Wave Ratio Reflection Coefficient using current settings FORMat LOGILIN and POL RECT Admittance 1 2 using current settings of INPut lMPedance and FORMAT POL RECT Impedance using current settings of INPut IMPedance and FORMAT POL RECT All basic measurements AVOltage BVOltage and PHASe Equivalent to MEAS AVOL BVCL PHASE MEASure TlMEout allows the measurement te timeout if the instrument has not locked to signal The range of the timeout is 0 to 30 seconds The default is 30 seconds MEASure TIMEout STATe defines if the timeout function is in use It sets the timeout function to ON C1 or OFF 0 The query option returns 1 or 0 All the above measurements are also dependant on whether CORRection STATe is ON or OFF y i Operation Output OUTPut ON OFF 1 0 Controls the front panel Test output signal The default is OFF The query option returns 1 or 0 Operation Complete lt HP1B gt OPC This command causes the Operation Complete bit in the Standard Event Status Register to be set when the Vector Voltmeter has completed all pending operations The Standard Event Status Register can be monitored to find when the bit 1s set using the ESR command or the Vector Voltmeter can be set to request service when the bit i
28. Uency BAND AUTO IDN INPut INPut iMPedance INPut IMPedance PC50 MEASure MEASure TIMEcut MEASure TIMEcut STATe OUTP Ut OPC RST TST SRE ESE ESR T8 STATus STATUS OPERation STATus OPERation CONDi tion STATus OPERation PTRansition STATus OPERation NTRansi tion STATUS OPERAtion EVENt STSTus OPERation sENA Ble SYSTem S STem ERRor SYS Tem KEY SYSTem FORMat TRG TRIGger TRiGger SQURce SWAT Parameter 3 lt nr f gt lt meas gt 4 lt nrt gt lt nrt gt lt nrt gt ON OFFI 110 ZO SHORT OPEN ON OFF 1 0 ON OFF 1 0 onlorr 1lo LINear LOGarithmic POLar RECTangular CARTesian lt nrf gt ON OFF 1 O lt nrt gt lt meas gt lt meas gt 4 lt nrf gt ONJOFF 1 0 ON OFF 70 lt nef gt 5 lt nr f gt 6 7 lt nrt gt 73 lt nri gt 7 lt nrf gt 7 NUMericiSTRing lt nrt gt ASCii FP amp 4 BUS FREErun Operation DESIG MED NOTES 1 Commands which allow a query option are indicated by y Commands where the query is mandatory are also shown with the query question mark in the Command Header column 2 Letters in CAPITALS are required the demainde r of the command can be added if desired for legibility 3 lt arf gt indicates Numeric Representation Flexible which is a forgiving real format described in IEEE 488 2 4 lt meas gt indicates AVOLtage BVOLtage APOWer A er eee DELa
29. V and dBm respectively magnitude ratio to dB and RHO magnitude to Return Loss n dB POLar Sets the results from vector measurements to ratio and phase angle RECTangular Sets the results from vector measurements to real and i imaginary components CARTesian Identical to RECTangular The default is LINear POLar The query option returns an ASCII string indicating the current state 3 44 E1089 Operation Frequency FREQuency Band BAND lt nrf gt Auto Ranging AUTO ONIOFF 1 O Sets the frequency band of the Vector Voltmeter lock circuits The band may be set explicitly or the Vector Volt meter can be allowed to auto range It is recommended that explicit band selection is used when possible to minimise lock time FREQuency BAND selects the frequency band explicitly The command forces BAND AUTO to OFF Bands are as follows Band Number Frequency band MHZ Band Number Frequency Band MHz 1 0 1 to 0 2 9 25 ta 50 2 6 2 to 0 6 10 50 to 80 3 3 6 to 1 11 80 to 150 4 1 to 3 12 150 to 250 5 3 to 5 13 250 to 500 6 5 to 8 14 500 to 1000 8 te 15 15 1000 to 2000 8 15 to 25 20 0 02 to 0 02 The default setting is automatic band selection The query option returns the current band FREQuency BAND AUTO selects explicit or automatic frequency band selection Frequency band 20 will not be selected When turned OFF the Vector Voltmeter remains in the current band The default is ON but is forced to OFF when the FREO B
30. a Wrap the instrument in heavy paper or plastic If shipping to Hewlett Packard office or service centre attach a tag indicating the type of service required return address model number and full serial number b Use a strong shipping container A double walled carton of 350 pound test material is adequate c Use a layer of shock absorbing material 70mm to 100mm 3 to 4 inch thick around all sides of the instrument to provide firm cushioning and prevent movement inside the container Protect the control panel with cardboard d Securely seal the shipping container e Mark the shipping container FRAGILE to ensure careful handling In any correspondence refer to the instrument by model number and full serial number 2 8 Operation Operation section 3 3 1 GETTING STARTED 3 2 INTRODUCTION This section provides complete operating information for the Vector Voltmeter The items covered include detailed descriptions of each front and rear panel key connector switch and display general and detailed operating instructions information on remote operation 3 3 OPERATOR S MAINTENANCE The only maintenance you as an operator should normally perform is replacement of the primary power fuse Fuses may be ordered under HP Part Number 2110 0305 T1 254 250V for 100 120Vac operation or under HP Part Number 2110 0360 T0 75A 250V for 220 240Vac operation Fault finding in the HP 8508A is aided by the self test
31. ake the conversion select REFL MEAS Z and SYSTEM IMPD NORM There is no need to recalibrate since the new display is computed from the same measurements as before e Other functions HOLD VALUE This function is useful when you are probing in a circuit especially dense circuits where the probe can easily slip onto another track When the signal disappears the display is frozen at the last reading To initiate this function configure the equipment for the measurement you want to make A B A B Now press HOLD VALUE The LED at the side of the key will illuminate Probe on the circuit Use the A probe if A only is active or the B probe if both are active Lift the probe when you are ready to take a reading The displayfs will freeze and hold the reading The function LED will flash to show that the hold mode is active To make a new measurement probe on the circuit The instrument will automatically re arm the function REF SELECT LOAD This function allows the use of a simple two resistor tee to enable you to make reflection casurements up to LOOMHz In this case a termination is used as the calibration standard Choose LOAD with the following test setup Source en HP8508A 908A Termination Power Splitter 908A Termination s Calibration Device Under Test Probe Tee Figure 3 14 Probe Inputs 3 18 Operation Source MPBSOSA Fower eis 1 908A Termination Splitter Calibrati
32. al Information Instrument Options Option 050 Provides an HP Model 85082 50 chm Input Module instead of the HP Model 85081 High Impedance Input Module Option 100 Deletes Input Module Documentation Options Extra Manual Set Option 910 Provides an additional copy of the Operating and Service Manual and the User s Guide English version Japanese User s Guide Option 030 Substitutes the Japanese version of the User s Guide for the English version French User s Guide Option 031 Substitutes the French version of the User s Guide for the English version German User s Guide Option 032 Substitutes the German version of the User s Guide for the English version italian User s Guide Option 033 Substitutes the Italian version of the User s Guide for the English version Spanish User s Guide Option 034 Substitutes the Spanish version of the User s Guide for the English version Support Option Extended Hardware Support Option W30 Provides an additional 2 years of return to HP hardware service support 1 7 ACCESSORIES SUPPLIED The accessories supplied with the instrument are Front Handle Kit with standard instrument An appropriate power cable see Section 2 An Operating and Service Manual A User s Guide Accessory kit comprising Accessory Kit Box 1 1540 0149 Square Plastic Box 1 1540 0034 Probe Tip 6 5020 0457 Probe Tip Nut Driver 1 8710 0084 Pre cut Foam Insert 1 9220 3728 Probe Tip BNC Adapto
33. at a static free workstation wherever practical De soldering When de soldering components ensure that the soldering iron is grounded Always use a metalized solder remover E1089 in J hm Adjustments Anti Static Freezer Spray When attempting to locate a temperature related fault use only an approved anti static freezer spray Anti Static Products Table 5 1 contains details of anti static products which are available from Hewlett Packard Table 3 1 Anti Static Products Praduct HP Part Number Anti static workstation kit 9300 0792 Metalized Solder Remover 8690 0227 Wrist strap and cord 9300 0970 5 4 EQUIPMENT REQUIRED All adjustment procedures contain a list of required test equipment The test equipment is also identified by callouts in the test setup diagrams where included If substitutions must be made for the specified test equipment refer to the Recommended Test Equipment table in section 1 of this manual for the minimum specifications It is important that the test equipment meet the critical specifications listed in the table ifthe Vector Voltmeter is to meet its performance requirements Note Use a non metallic tool whenever possible for example HP Part Number 8830 0024 5 5 POST REPAIR ADJUSTMENTS Table 5 2 lists the adjustments related to repairs or replacement of any of the assemblies 14 1 y ee nr gt OD L Adjustments a 5 6 RELATED ADJUSTMENTS Table 5 2 Related Adjustments
34. ator over its operating range and check the frequency response variation In a circuit with adjustable gain the HP 8508A METER display is an aid to tuning Use of the meter display is covered in the next example Any unmodulated RF signal in the frequency range 100kHz to 1GHz can be used as a source for these measure ments This includes a source that is part of a larger device under test This diagram shows all the keys you will need to make the measurements Os Oo 00 Oe Ds o O_O 100 Ih Figure 3 4 Front Panel Keys In the descriptions throughout this section keys on the instrument are described by writing the key name in square brackets for example PRESET Keys that have multiple selections are described by writing select followed by the key name in square brackets then the required function in bold type for example Select REFL MEAS SWR When you press this type of key the next valid state will be selected Press the key the required number of times to light the LED beside the state requested Some selections are only available in combination with other keys so don t worry if all the selections are not available 3 10 Operation Where a function is accessed using the alternative function of a key the function is described by showing SHIFT then the function name which appears in blue on the front panel for example to obtain SHIFT REF this would be described as press SHIFT then SAVE
35. atures from 0 Centigrade to 55 Centigrade Humidity The instrument may be operated with humidity up to 90 up to 40 Centigrade However the instrument should also be protected from temperature extremes which may cause condensation within the instrument Altitude The instrument may be operated at altitudes up to 4600m 15000ft E1089 gt EN installation 2 8 MATING CONNECTORS Table 2 3 lists the connectors which mate with the instrument ports Table 2 3 Mating Connectors Connector Mating Connector Part Number PROBE POWER m 5060 0466 1250 1448 1250 0448 1250 0448 see Table 24 2 9 RACK MOUNTING Figure 2 2 illustrates the Rack Mount Kits available for use with the HP 8508A N 4a 2 1089 Installation 2 10 HEWLETT PACKARD INTERFACE BUS HP IB This section contains information for installing the HP 8508A Vector Voltmeter into a Hewlett Packard Interface Bus HP IB system The HP IB is Hewlett Packard s implementation of IEEE Standard 488 1978 Digital Interface for Programmable Instrumentation This standard defines a physical interface and protocol which enables the remote control of instrumentation systems 2 11 HP 1B CONNECTOR Logic Levels The HPAB logic levels are TTL compatible Le the true 1 state is 0 to 0 5V DC and the False 0 SIGNAL COMMON state is 2 5 to 5V DC SIGNAL COMMON TWISTED WITH PIM i SHIELD ATN E El 0 406 0105 D102 2101 n
36. ch it does not implement 3 The device received a Group Execute Trigger GET inside a program message Bit 4 Execution Error EXE This bit indicates that the device detected an error while trying fo execute a command It indicates that 1 A lt PROGRAM DATA gt element received in a command was outside the legal range for the device or incon sistent with the operation of the device 2 The device could not execute a valid command due to some device condition Bit 3 Device dependent Error DDE A device dependent error is any device operation which did not execute properly due to some internal condition such as overrange It indicates that the error was not a command query or an execution error Bit 2 Query Error QYE This bit indicates 1 An attempt to read data from the Output Queue when no data was present 2 That data in the Output Queue was lost An example of this would be queue overflow Bit 0 Operation Complete OPC This bit indicates that the device has completed any pending operations and is ready to accept new commands This bit is generated only in response to the Operation Complete OPC command SESR Operation The SESR operates in the same manner as the Event Registers described earlier It can only be cleared by 1 a Clear Status command CLS 2 reading it ESR 3 a power on transition The associated Standard Event Status Enable Register is written with the Enable Status ESE command
37. channel signal is removed 40 50 Addr 708 I Vector Voltmeter Address 69 ON INTR 7 CALL intr I Set up SRQ interrupt handler call 70 80 CLEAR Addr 3 Clear interface 0 OUTPUT Addr FRET EME DE i Reset Vector Voltmeter 100 i 110 OUTPUT Addr ESE 36t i Enable SRQ on Query or Command Error 140 I 150 OUTPUT Addr STATUS OPER PTR 4 i Enable SRQ when 8508A becomes 180 OUTPUT Addr STATUS OPER ENAB 4 i Unlocked 200 210 OUTPUT Addr SRE 160 Generate SRQ on above conditions 230 i 240 ENABLE INTR 752 Enable SRO interrupts in BASIC 250 REPEAT 260 OUTPUT Addrs SYST KET f I Am incorrect Command to generate an SRO 270 WALT 5 280 UNTIL 1 0 Repeat Forever 290 END 300 310 320 SUS Intr 330 DIM Err messages 100 340 Addr 708 350 OUTPUT Addr STB 360 ENTER Addr Stat Read Status Byte 370 IF BIT Stat 5 THEN 380 OUTPUT Addr ESR Read amp Clear Standard Event Register 390 ENTER Addr Std_ event 400 IF BIT Std_event 5 THEN PRINT Command Error 410 IF BIT Std_event 2 THEN PRINT Query Error 420 OUTPUT Addr SYST ERR 430 ENTER Addr Err_message 440 PRINT Err_message 450 END IF 3 33 E1089 Operation 468 F BiT Stat 7 THEN 470 PRINT HPBSO8A UNLOCKED 480 REPEAT 490 OUTPUT Addr STATUS OPER COND 500 ENTER Addr Condition 510 UNTIL BET Condition 2 0 1 Wait for lockup again 520 PRINT HP amp 508A LOCKED 530 OUTPUT Addrz CLS i Cl
38. ctor Voltmeter The HP 85084A is shown in Figure 1 1 On the title page of this manual is a Microfiche Part Number This number can be used to order 4x 6 inch micro film transparencies of the manual Each microfiche contains up to 96 photo duplicates of the manual pages 1 2 SPECIFICATIONS Instrument specifications are listed in Table 1 2 of the Probe Module Insert These specifications are the perform ance standards or limits against which the instrument is tested The Probe Module Insert document contains the specifications relevant when the Probe Module ts inserted into the HP 8508A Vector Voltmeter mainframe 1 3 SAFETY CONSIDERATIONS This instrument is a Safety Class 1 instrument provided with a protective earth terminal The instrument and manual should be reviewed for safety markings and instructions before operation The WARNINGS indicate the possibility of personal danger and CAUTIONS indicate the possibility of instrument damage 1 4 INSTRUMENTS COVERED BY MANUAL Attached to the instrument is a serial number plate The serial number is in the form XXXXUXXXXX The first four digits and the letter comprise the serial prefix which is the same for all identical instruments The serial prefix only changes when a change is made to the instrument The last five digits comprise the serial number which is unique for each instrument The content of this manual applies to instruments with the serial prefix es listed under SERIAL NUMBERS on th
39. ds General Information A typical setup includes a source which may be part of the device to be tested a reference path and a measure ment path Cables adapters and other accessories required depend on the application The following diagram shows an example setup HP8508A Ar Input pr input Moduie Under Test reference Path f Measurement Path Device Under Test Figure 1 2 Typical Probing Set up In order for the source to be suitable for use with the HP 8508A it has to meet certain specifications It must produce a stable CW signal at the frequency of interest with no modulation 1 6 OPTIONS The standard instrument is supplied with front handles HP Part Number 5062 3989 while rack mounting flanges or bail carrying handle and front cover are available as options Mechanical Options Bail Handle Option 001 Adds bail carrying handle rugged feet and front panel storage cover Rack Flange Kit Option 908 HP Part Number 5062 3977 This kit contains all necessary hardware and installation instructions for mounting the Vector Voltmeter not fitted with front panel handles in a rack with 482 5 millimeter standard 19 inch spacing Rack Flange Kit Option 913 HP Part Number 5061 4071 This kit contains all necessary hardware and installation instructions for mounting a Vector Voltmeter with front panel handles in a rack with 482 4 millimeter standard 19 inch spacing E1089 1 3 Gener
40. e the first frequency on the synthesizer Select DELAY Press SAVE VALUES to save the measurement Set the synthesizer to the second frequency 4kHz and read the delay E1089 3 19 Operation d Z0kHz Receiver The HP 8508A can be used with the input module extender HP part number 08508 60032 as a 20kHz receiver This feature can be used to allow magnitude and phase measurements on a 20kHz signal For example to make delay measurements by amplitude modulating an RF signal In this case the HP 8508A measures the phase change in the modulation envelope which can be converted to delay Modulation Source Wee RF Source HP 85084 input Module Extender Calibrate Device under test Detector Figure 3 16 20kHz Receiver Setup 1 Set the RF source to the frequency of interest Ensure that AM is on and set the amplitude to give approximately 10dBm at the detector input Set the modulation source to 20kHz at a level compatible with the RF modulation input Using an oscilloscope check that the detected signal is an undistorted sinewave Reset the AM percentage and the modulation source level if necessary 2 To cal brate the circuit configure the equipment as shown in Figure 3 16 without connecting the device to be tested 3 On the HP 8508A press PRESET to return the HP 8508A to a known state Press B A PHASE to measure amplitude on Display 1 and phase on Display 2 Press LOCK RANGE SHIFT VIEW RANGE and
41. e title page of this manual An instrument manufactured after the printing of this manual may have a serial number prefix that is not listed on the title page The unlisted serial number prefix indicates that the instrument is different from those described in this manual The manual for this new instrument is accompanied by a Manual Changes supplement This supple ment contains change information that explains how to adapt the manual to the new instrument In addition to change information the supplement may also contain information for correcting errors in the manual To keep this manual as current and as accurate as possible Hewlett Packard recommends that you periodically request the latest Manual Changes supplement The supplement for this manual is identified by the manual print date and part number both of which appear on the manual title page Complimentary copies of the supplement are available from Hewlett Packard For information concerning a serial number prefix that is not listed on the page or in the Manual Changes supplement contact your nearest Hewlett Packard office General Information 1 5 DESCRIPTION The HP 8508A Vector Voltmeter is a dual channel autoranging receiver which measures the voltages of two CW signals and the phase difference between them The following diagram shows the vector 1 relationship between two signals at the same frequency and the way that one is used as a phase reference in the HP 85084
42. ear ALL Status Structures 540 END IF 550 i 260 ENABLE INTR 7 i re enable SRQ 570 SUBEND Figure 3 23 SRQ Enabling and Handling Sending the Service Request Message The Vector Voltmeter sends the Service Request message in either local or remote mode When it is sending the message the front panel S annunciator lights The message is cleared when a serial poll is executed by the controller or when a CLS Clear Status instrument command is received Sending the Status Byte Message The Vector Voltmeter sends the Status Byte message after receiving a Serial Poll Enable SPE bus command and when addressed to talk It complies with IEEE488 2 so bits 4 and 5 are defined as MAV and ESB respectively The Vector Voltmeter also makes use of bit 7 as the Operation Status Register Summary Bit but all other bits are unused The bit pattern of the Status Byte is shown in Figure 3 25 Once the Vector Voltmeter receives the SPE bus command it is no longer able to alter the Status Byte Ifa bit has been enabled and that condition occurs after bit 6 has been set the bit is stored in a buffer and is read the next time the Vector Voltmeter receives the SPE bus command The Status Byte and any Service Request message pending will be cleared if a CLS Clear Status instrument command is received by the Vector Voltmeter E1089 Operation lien Status Reporting The IEEE 488 2 Standard describes a status reporting structure so that control
43. eep Speed 0 2us div Model HP 8642B HP 11636A HP 456A Datron 42004 HP 909A Opt 012 HP 33264A HP 84964 G Opt 890 HP 117134 HP 436A or HP 438A HP 8482A HP 542004 HP 11570A HP 08508 60032 P Performance A Adjustment T Troubleshooting O Operation NOTE The HP 8496A G attenuator should be calibrated within 0 03dB for the 10dB through 60dB steps E1089 E General Information 1 6 Installation Installation Section 2 2 1 INTRODUCTION This section provides installation instructions for the Hewlett Packard Model 8508A Vector Voltmeter and its accessories This section also includes information about initial inspection and damage claims preparation for use packaging storage and shipment 2 2 INITIAL INSPECTION WARNING IF THERE IS ANY SIGN OF SHIPPING DAMAGE TO THE INSTRUMENT DO NOT APPLY POWER RETURN THE INSTRUMENT TO THE NEAREST HEWLETT PACKARD OFFICE FOR CHECKING Inspect the shipping container for damage If the shipping container or cushioning material is damaged it should be kept until the contents of the shipment have been checked for completeness and the instrument has been checked mechanically and electrically The Performance Tests check the complete specification of the instrument if the contents of the shipment are incomplete if there is mechanical damage or defect or if the instrument per formance fails to meet specification notify the nearest Hewlett Packard
44. etup code is being used This will appear as tSt nnan tSt indicates that the instrument is in the setup mode and nnnn is the current setup code Use the UP DOWN Arrow keys to set up test code 2 in Display 2 Press HOLD VALUE and check that the indicator LED is ON 6 Adjust the A3L1 core to obtain a maximum reading in Display 2 7 Press HOLD VALUE to cancel the function 8 Use the UP DOWN Arrow keys to set up test code 3 in Display 2 Press HOLD VALUE and check that the indicator LED is ON 9 Adjust the core of A3L2 to obtain a maximum reading on Display 2 10 Press HOLD VALUE to cancel the function 11 Replace the HP 8508A top cover 5 6 E1089 Adjustments foram orca aes ee CENTRE FREQUENCY ADJUSTMENT CENTRE FREQUENCY oe AS R151 PHASE SHIFT ADJUSTMENT ge A3 R178 CHANNEL GAIN ADJUSTMENT CHANNEL B FILTER CHANNEL A FILTER ADJUSTMENT 2 ASL k Figure 5 2 IF Assembly Component Location EUA naL Tag w TE pnl 0 a A NA A endl A SE nti Se LAINE sn armer Ta 5 7 E1089 Adjustments To equalize the A and B Channel phase shift DESCRIPTION An internal test routine is used for this adjustment EQUIPMENT No external test equipment is required for this adjustment PROCEDURE 1 Remove the Input Module from the instrument 2 Switch on the equipment and allow to warm up for 30 minutes Note Since the Input Module is not installed in the
45. ge is selected by the rear panel switch CAUTION Before connecting the instrument to a power outlet ensure that the line voltage selector is correctly set and that a fuse of the correct rating is fitted Fuse ratings are given in the table below Table 2 1 Fuse Ratings Nominal Fuse Line Rating 100 120V T1 25A 250V 2110 0305 220 240V T0 754 250V 2110 0360 HP Part Number 32 E1089 Installation 2 6 POWER CABLE The instrument is equipped with a three wire power cable When connected to a power outlet this cable grounds the instrument case The type of power cable shipped with each instrument depends on the country of destination Refer to Figure 2 1 for part numbers of the power cable and plug configurations available The number shown below each plug is the Hewlett Packard part number of a power cord equipped with that plug If the appropriate power cord is not included with the instrument notify the nearest Hewlett Packard Sales and Service Office and a replacement will be provided CA ER Fr Rita NER eas iets i tr Nat EEE 8120 2104 8120 1359 820 1689 8120 1351 8120 1378 US 8120 2986 8120 4271 8120 4754 AP Figure 2 1 Plug Configurations The colour code used in each over cable is given below Table 2 2 Colour Codes Line Brown Neutral Blue Ground Green Yellow 2 7 OPERATING ENVIRONMENT Temperature The instrument may be operated in temper
46. his will be of the form ASCII characters 1 8 followed by eight data bytes in IEEE 754 1985 double precision format E1089 3 39 ee Operation ra SOMET FOR Gi HP IB Command Set Summary Description Averaging Value Calibration Capability Clear Status Configure Measurement Correction A Value B Value Phase Value Normalize Impedance Termination Perform Normalization Normalization State Direct Analog Output Display State Fetch Results Continuous readings Format Frequency Band Auto Ranging Identification Input Impedance Module Type Measure Timeout Timeout State Output Test Signal Operation Complete Reset Self Test Service Request Enable Standard Event Enable Standard Event Register Status Byte Request Status Control Operation Status Condition Register Positive Transition Filter Negative Transition Filter Event Register Enable Mask System Error Register Key Format Trigger Trigger Setup Source Wait to continue Tabie 3 2 Command and status message summary Query 1 y I o E A AX A XK Ke IKK MK lt lt lt K AX XA J lt XXAX lt lt yx Pe En Command Header 2 AVERage COUNt CAL CAP ELS SENSe CORRection CORRection DATA A CORRection DATA 8 CORRectio PHASe CORRect ion IMPedance CORRection TERMinatior CORKection PERFO rm CORRection STATe DAhNalog DISPiay STATe FETCh FETCH CONTinucus FORMat FREQuency FREQuency BAND FREQu
47. it receives the Local message GTL or the Clear Lockout Local message REN false If not in Local Lockout mode the instrument switches to local when the front panel LCL key is pressed NOTE Return to local can also be accomplished by setting the Vector Voltmeter s LINE switch to OFF then to ON However this technique has some disadvantages a It defeats the purpose and advantage of local lockout that is the system controller loses control of a system element b There are several HP IB conditions which reset to default states at turn on Addressing The Vector Voltmeter s HP IB address is stored in permanent memory so that it is remembered through power cycling The address can be set from the front panel as follows a Press SHIFT ADDRESS to display the current address b Use the arrow keys to select the required address 0 30 which becomes effective immediately The instrument s normal address setting is 8 c Press SHIFT ADDRESS or any other function to return fo normal operation The Vector Voltmeter can be Addressed to Listen Addressed to Talk or Unaddressed It is Addressed by putting either its Listen Address HP IB Address 32 or its Talk Address HP IB Address 64 onto the bus in command mode ATN true amp IFC false It remains Addressed to Listen until it receives its Talk Address or a Universal Unlisten command It remains Addressed to Talk until it receives its Listen Address or an Untalk com
48. l be covered to show how some of the features of the HP 8508A can be used to make your measurements easier The measurement examples will use 50 ohm devices refer to the following section for details of configuring the HP 8508A for 50 ohm inputs Measurements in a 50 ohm system 50 ohm measurements can be made directly when the HP 8508A is fitted with the type N HP 85082 Input Module or by using adapters with the probes of the HP 85081 Input Module The HP 11536A Feedthru is part of the HP 115704 Accessory Kit The following diagram shows how to connect the probe adapters to make 50 ohm meas urements 50 obm in line 50 ohm Terminated Probe Probe 50 ohm oth 50 ohm 50 ohm 908A 50 ohm source load source Termination 115354 Probe Tee 11536A Probe Tee Figure 3 8 Probe to 50 ohm Options In this example measure the 3dB point of a low pass filter that cuts off at around SOMHz The circuit includes a source and a power splitter which is used to obtain a reference signal The filter is preceded by a 6dB pad to minimize out of band reflection problems 3 14 E 1089 Operation Measurement details 1 Connect the equipment as shown below Press PRESET to get the instrument to a known state then B to measure the filter output To frequency counter opfional HP85084 A Input 50 ohms J1 J2 y 33 Power Sptitter A Low Pass Filter J7 Pad ES Es amp HF8SO084 8 Input 50 ohms J4 J6 Figure 3 9 Test Setup
49. lers know how to ask a device such as the Vector Voltmeter for its status Figure 3 24 shows an overview of the status reporting structure tatus Data Structure I i s a Summary Status t A Status Byte Register Service Request Indication lt 1 Y 488 1 Service Request Function e IS SRG rey Figure 3 24 TEEE488 2 Status Reporting Structure Overview in tri Jam ao CO WO Operation Status Data Structures IEEE488 2 allows the Status Byte to contain up to seven single bit summary messages from data structures but the Vector Voltmeter only makes use of bits 4 and 7 as described earlier in Sending the Status Byte Message The status data structures are queues or event registers and the summary bits are used as follows Bit 4 MAV reports the status of the Output Queue Bit 5 ESB reports the status of the Standard Event Status Register Bit 7 reports the status of the Operation Status Register Figure 3 25 shows the Standard Status Model for IEEE488 2 instruments Two of the Vector Voltmeter s data structures are not shown but are described later The Operation Status data structure is similar to the Standard Event Status data structure and the Error Queue is summarised in the error bits of the Standard Event Status Register as 8 s 5 4 2 E oe b e tw g g eg Bee ra 7 D au w Ps oo ae i E L L Z 3 E E
50. llows the state of the function to be checked remotely Figure 3 22 shows a typical command MEASURE AVOLTAGE lt ecro lt lf gt A A A Make a measurement Termination Sequence Return the result Parameter to measure Figure 3 22 A Typical Command Triggered Measurements A feature only available via remote programming is selection of free run or HP IB triggering With triggering set to free run the Vector Voltmeter measures continuously outputting data to the display and Gf requested the HP IB as each measurement cycle is completed When the trigger source is set to BUS the Vector Voltmeter will make triggered measurements A trigger is initiated by the trigger message a Group Execute Trigger HP IB command or a TRG Instrument command In triggered mode internal settings can be altered but the instrument is inhibited from measuring and sending results to the front panel or the HP IB until a trigger is received When triggered the instrument completes one cycle of the current measurement and then waits for another trigger The results of the completed measurement are held and can be obtained by using the FETCh or MEASure command Returning the Vector Voltmeter to local contro forces the trigger source to the freerun mode E1089 Operation PESONEN teh SYSTEMS Sending the Data Message The Vector Voltmeter sends Data messages when addressed to talk and has data to output The output format fo
51. mand Power on Default Conditions Several HP IB parameters are reset at power on The parameters and their default conditions are listed below HP IB Local Mode Unaddressed Service Request Enable Register cleared Status Reporting Structure cleared Trigger Source Freerun Display State active Should the Vector Voltmeter fail part of its power on test sequence the Error code will be placed in the Error Queue See also SYSTem ERRor 3 28 E1089 Operation Data Messages The Vector Voltmeter communicates on the interface bus primarily with Data messages Data messages consist of a sequence of bytes sent over the bus data lines when the bus is in the data mode ATN false The Vector Voltme ter receives Data messages when addressed to listen and sends Data messages or the Status Byte message when addressed to talk All instrument operations available in local mode can be performed in remote mode via Data messages except for changing the LINE switch Receiving the Data Message The Vector Voltmeter responds to Data messages when in remote mode REN true and addressed to listen Instrument Commands Instrument commands are sent as data messages Commands may be linked together using appropriate punctua tion as defined in the IEEE 488 2 standard Allowable commands for the Vector Voltmeter are described in Table 3 2 Either upper or lower case characters are accepted Many commands have a query option that returns results or a
52. mately 1 0 Display 2 should be off Press B A PHASE to display the input phase difference in Display 2 The reading should be approximately 0 deg 8 SET A REFERENCE Press SHIFT then SAVE REF to store the current measurement as a reference and normalize readings to the saved reference value The displays should now read exactly 1 0 magnitude and 0 0 deg phase NOTE DISPLAY 1 reads 1 0 REL and DISPLAY 2 reads 0 0 DEG REL Operation Figure 3 6 Displays 5 RELATIVE MEASUREMENT Now insert the cable as shown in Figure 3 5 The readings are now of the voltage ratio and phase difference caused by the cable using the reference set in step 8 Select DISPLAY dB to read the cable insertion loss in dB The phase difference can be used to calculate the cable s electrical length 16 REAL AND IMAGINARY Instead of magnitude and phase you can show the measurement results as real and imaginary components Select FORMAT REAL amp IMAG to see results in this form NOTE DISPLAY 1 reads ohm and DISPLAY 2 reads johm DISPLAY T car Figure 3 7 Displays WHAT YOU HAVE ACHIEVED You have made voltage measurements A and B and a vector ratio measurement B A MAG B A PHASE and normalized the ratio to a reference E1089 3 13 Operation 3 9 ADVANCED MEASUREMENTS This section will cover some simple network analysis measurements using the HP 8508A and a companion source Transmission and reflection measurements wil
53. meter PACKARD HERSTELLERBESCHEINIGUNG Hiermit wird bescheinigt da das Gerat System 85084 in bereinstimmung mit den Bestimmungen von Postverf gung 1046 84 funkenst rt ist Der Deutschen Bundespost wurde das Inverkehrbringen dieses Ger tes Systems angezeigt und die Berechtigung zur berpr fung der Serie auf Einhaltung der Bestimmungen einger umt Zusatzinformation f r Me und Testger te Werden Me und Testger te mit ungeschirmten Kabeln und oder in offenen Me aufbauten verwendet so ist vom Betreiber sicherzustellen da die Funk Entst rbestimmungen unter Betriebsbedingungen an seiner Grundst cksgrenze eingehalten werden MANUFACTURER S DECLARATION This is to certify that this product 8508A meets the radio frequency interference requirements of directive 1046 84 The German Bundespost has been notified that this equipment was put into circulation and was granted the right to check the product type for compliance with these requirements Note If test and measurement equipment is operated with unshielded cables and or used for measurement on open set ups the user must ensure that under these operating conditions the radio frequency interference limits are met at the border of his premises General Information General Information Section I 1 1 INTRODUCTION This service manual contains information required to install test adjust and service the Hewlett Packard Model 8508A Ve
54. n FEI SIGNAL COMMON TWISTED WITH PIN 10 iCD TO sra Mating Connector SIGNAL COMMON TWISTED WiTH pin 9 20 O i re SIGNAL COMMON TWISTED WITH PIN 8 11120 A woac HP 1251 0293 SIGNAL COMMON TWISTED WITH PIN 7 Cl nero Amphenol 57 302040 SIGNAL COMMON TWISTED WITH PIN 6 UGE EV pay REN GD Et eo pios 1108 A oios 0107 Gl o103 2 13 1 2 TYPE 87 MICRORIBBON CONECTOR Figure 2 3 HP IB rear panel Connector The HP IB connector on the rear panel of the HP 8508A provides the physical interface to connect the HP 8508A into an HP IB system Figure 2 3 illustrates the connector pin configuration Devices in the HP IB system may be interconnected in any suitable arrangement star delta etc using the HP IB cables listed in Table 2 4 However the cable length restrictions should be observed Installation 2 12 HP IB CABLES Table 2 4 lists the HP IB cables available Table 2 4 HP IB Interface Cables HP Part Numbers Cable Lengths HP 10833A im 3 3ft HP 10833B 2m 6 6ft HP 10833C 3m 13 2ft HP 10833D 0 5m 1 6ft To achieve design performance restrictions are placed on the length of the HP IB system cable as follows 1 The total length of HP IB cable use to interconnect devices on the HP IB must not exceed 2 meters 6 feet times the number of devices in the system 2 The total length of HP IB cable used to interconnect all devices must not exceed 20 meters 65 feet 2 13 HP
55. n dBm in a 50ohm system The conversion of voltage to power uses the value set with the SYSTEM IMPD key the default value being 50 ohms Press POWER MEAS again to return to the voltage measurement mode 6 SINGLE CHANNEL MEASUREMENT BCHANNEL Most measurements with the HP 8508A will be done using the B probe leaving the A probe in place as a reference The B channel is much more sensitive since the A channel already provides the signal to which the instrument is locked Press B to display the B input voltage in Display 2 The A reading remains in Display 1 unless you turn it off by pressing the A key The A probe must still be connected in order to keep the instrument locked Display 2 shows E1089 3 11 Operation the B channel residual noise level of around 10uV when the probe is not connected 7 DUAL CHANNEL MEASUREMENT The HP 8508A can display the ratio of the signals in its two channels making it unnecessary to calculate the results of ratio measurements Connect the two probes to the source output using a tee as shown in the following diagram Source HPS5084 A input B Input Probe and BNC Adaptor Cable step 9 Figure 3 5 Two Probe Connection Select DISPLAY UNITS to display the levels as voltages The A and B voltages in Displays 1 and 2 respectively should read approximately the same value Press B A MAG to show the voltage ratio of B to A in Display 1 The reading should be approxi
56. ns Probing measurements with external source Transmission measurements in 50 ohms Probe Inputs Transmission measurements in 50 ohms Direct Inputs Reflection measurements in 50 ohms Probe Inputs Reflection measurements in 50 ohms Direct Inputs Remote Operation The Hewlett Packard Interface Bus HP IB Capability Local and Remote Operation Addressing Power on Default Conditions Data Messages Instrument Commands Service Requests Status Reporting HP IB Response Formats HP IB Command Set Summary Command Reference SECTION 4 PERFORMANCE TESTS introduction SECTION 5 ADJUSTMENTS Introduction Warm up Time Safety Considerations Equipment Required Post Repair Adjustments Related Adjustments Adjustable Components Power Supply Adustments 12 0V 12 0V and 5 0V IF Assembly Adjustments Set up the centre frequency of the Channel A and B Bandpass filters To equalize the A and B Channel phase shift Set up the amplitude path gain using an external 20kHz 100m V reference source Search and Lock Assembly Adjustments Set the centre frequency of the 1 62MHz and 32 4MHz Oscillators 3 9 3 9 3 9 3 9 3 13 3 14 3 14 3 22 3 22 3 23 3 24 3 25 3 26 3 27 3 27 3 27 3 28 3 29 3 29 3 29 3 31 3 34 3 39 3 40 3 42 4 1 5 1 5 1 5 1 5 2 7 5 3 5 3 5 4 5 6 5 8 5 9 5 12 5 12 1089 General Information Karen gt ein s om gt Figure 1 1 The HP 8508A Vector Volt
57. nt panel 6 Press HOLD VALUE to cancel the function 7 Use the UP DOWN Arrow keys to set up test code 2 in Display 2 Press HOLD VALUE and check that the indicator LED is ON 8 Adjust the core of A4L3 slowly until the UNLOCK light extinguishes 9 Press HOLD VALUE to cancel the function 10 Replace the HP 8508A top cover Adjustments 32 4MHz OSCILLATOR ADJUST Ad 13 1 62MHz OSCILLATOR ADJUST As RBS CAS UNLOCK INDICATOR ia En ans Te p jik wae Meee hits ate 5 15 Figure 5 5 Search and Lock Assembly Adjustment Locations E1089 Adjustments ona
58. ommand If in remote mode the Vector Voltmeter responds to the Local Lockout message by disabling the front panel LCL key The local lockout mode prevents loss of system control due to accidentally pressing front panel keys When in local lockout mode the Vector Voltmeter can be returned to local only by the controller using Local or Clear Lockout Local messages or by setting the LINE switch to OFF and ON Receiving the Clear Lockout Set Local Message The Clear Lockout Local message is the means by which the controller sets the Remote Enable REN bus control line false The Vector Voltmeter returns to local mode full front panel control when it receives the Clear Lock out Set Local message When the Vector Voltmeter goes to local mode the front panel R annunciator turns off 3 30 E1089 Operation DESMINED FOR Receiving the Pass Control Message The Vector Voltmeter does not respond to the Pass Control message since it cannot act as a controller Receiving the Abort Message The Abort message is the means by which the controller sets the Interface Clear IFC bus control line true When the Abort message is received the Vector Voltmeter becomes unaddressed and stops talking and listening Sending the Status Bit Message The Vector Voltmeter has no Parallel Poll capability and makes no response to the status bit message Other Messages Other messages sent by the Vector Voltmeter are responses to the query option of some
59. on Type N A Tee Device Under Test Figure 3 15 50 ohm Inputs Connect the termination calibration standard Press SAVE REF Replace the termination with the device under test DUT Read result LOCK RANGE Using this function provides a faster lock response in automatic systems and when making repetitive measurements near a specification range boundary This function overrides the automatic selection of requency lock range MAG RANGE This function has two uses First it overrides the automatic selection of the magnitude display range allowing control of display resolution Second it enables you to control the rear panel output range useful when using auxilary equipment CAL TEST This function controls the test output and also performs an internal calibration You should use this function regularly to ensure that the instrument maintains its optimum performance This function should be used after instrument warm up allow a 30 minute warm up period In addition if the instrument is used in a constant environment this function should be used at least once per day DIR ANALG OUT This function activates the rear panel outputs and locks the instrument state Using the rear panel outputs for narrowband sweeps gives a faster response SHIFT DELAY This function enables you to make single point delay measurements by converting the measured phase difference to a delay measurement Set for transmission Choos
60. on A Serial Poll of an IEEE488 2 instrument produces the same effect TEEE488 2 provides a further command STB to read the Status Byte If this command is used the state of the MSS bit is returned and the bit is not cleared when read These differences arise because IEEE488 2 defines a status reporting structure which extends the specifications of the original standard In IEEE488 2 the Status Byte summarises the underlying status data structures and the concept of enabling service requests is defined E1089 Operation Enabling Service Requesis The service request enabling operation is shown in Figure 3 24 The user can set bits in the Service Request Enable Register SRER These bits correspond to bits in the Status Byte If a bit is set in the SRER it enables the instrument s ability to generate an SRO when the corresponding event occurs For example setting bit 4 in the SRER will produce a service request when the MAY bit is set If a bit is set in the Status Byte but not enabled in the SRER it cannot cause bit 6 to be set and consequently will not initiate an SRQ although it will be read when the Status Byte is read Refer to Figure 3 23 for an example of SRO enabling and handling 19 f HP8508A Example HP 18 SRQ Enable Handling Program 20 30 This program continually sends an illegal command to the 85084 35 and deals with the returned SRQ It also reports the 8508A 37 going out of lock when the A
61. orm to the standards set by document IEEE 458 2 1987 Codes Formats Protocols and Common Commands for use with ANSI TEEE Std 488 1 22 January 1937 Consult the standards document for details of the commands and structures recommended For more information about HP IB refer to IEEE Standard 488 1 or the identical ANSI Standard MC1 1 the Hewlett Packard Electronic Systems and Instruments catalog the booklet Improving Measurements in Engineer ing and Manufacturing HP part number 5952 0058 and Tutorial Description of the Hewlett Packard Interface Bus HP part number 5952 0156 Nov 87 Anyone who is unfamiliar with the IEEE 488 Standards should read the Tutorial Description as an introduction HP IB Capability This section gives a general description of HP IB capabilities as they apply to the Vector Voltmeter The instru ment s command set is summarised in Table 3 2 and command details are given in the Command Reference section HP IB system operation normally relies on three types of bus device behaviour as follows A LISTENER is capable of receiving data over the bus when addressed to do so There can be multiple listeners simultaneously active A TALKER is capable of transmitting data over the bus when addressed to do so There can be only one active talker at a time A CONTROLLER specifies the talker and listener s for an information transfer including itself There can be only one active controller at a
62. ost of a lower measurement rate Lower values increase the measurement rate and may Increase measurement variation Range 0 to 10 Default 5 The number of internal readings made is two raised to the power of AVERage COUNt The query option returns the current setting Calibration CAL Performs an internal device calibration A value of 1 will be returned if the calibration fails A value of O indicates successful calibration Capability lt HPIB gt CAPabi Lity Returns the instrument s HP IB capability string as follows SH1 AH1 T6 TEO L4 LEO SR1 RL1 PPO DC1 DT1 C0 E2 Clear Status lt HP1B gt CLS Clears the contents of the status register and associated status data structures This command should be used as part of remote instrument preset Configure Measurement SENSE lt meas gt This command is used to configure the measurement that the Vector Voltmeter will make and the results it will return in response to a measurement query Default is AVOLtage Options for lt meas gt are listed in the Measure section Operation Correction CORRection DATA A Value lt HPlga gt A lt nri gt B Value lt HPtB gt 28 lt nrf gt Phase Value lt HPIB gt PHASe lt nrf gt Normalize Impedance IMPedance ON OFF 10 Termination TERMination SHORT OPEN ZO Perform Normatization SPERF orm Normalization State STATe ONJOFFITI O The correction commands define the normalization values and state Co
63. ould be tested with a DVM If the supply voltages are correct the fault may be on the Search and Lock Asssembly A4 3 Remove the HP 8508A top cover to allow access to the adjustments 4 Connect the DVM input to the Test Points shown in the following table and make the appropriate adjustments for the correct voltage levels Test Point Adjustment Voltage Tolerance A2 TP3 A2R16 12 0V 0 1V A2 TP4 A2R1S 12 0V 0 1V A2 TP2 A2R11 5 0V 0 05V A2 TPI GND 5V 12V R16 12V TPs 5V TP2 VB TF4 Figure 5 1 Power Supply Adjustment Locations 5 Replace the HP 8508A top cover E1089 Adjustments Adjustments 5 9 IF ASSEMBLY ADJUSTMENTS Set up the centre frequency of the Channel A and B Bandpass filters DESCRIPTION The 20 kHz centre frequency for Channel A and B is set up using an internal test routine EQUIPMENT No external test equipment is required for this adjustment PROCEDURE 1 Remove the Input Module from the instrument 2 Switch on the equipment and allow to warm up for 30 minutes Note Since the Input Module is not installed in the mainframe the HP 8508A will display the error message Err 601 This reading should be ignored 3 Remove the HP 8508A top cover to allow access to the adjustments 4 Adjust the cores of A3L1 and A3L2 to the top of the coils 5 Select PRESET SHIFT POWER MEAS to put the instrument into the setup mode The Displays will now indicate which s
64. r each message is shown in Table 3 2 Receiving the Remote Message The Vector Voltmeter switches fo remote operation upon receipt ofthe Remote message The Remote message has two parts The Remote Enable bus control line REN set true and A Device Listen Address received once while REN is true When the Vector Voltmeter switches to remote the front panel R annunciator turns on Receiving the Local Message The Local message is the means by which the controller sends the Go To Local GTL bus command If addressed to listen the Vector Voltmeter returns to front panel control when it receives the Local message If the instrument is in local lockout when the Local message is received front panel control is returned but lockout is not cleared Unless it receives the Clear Lockout Local message the Vector Voltmeter will return to local lockout the next time it goes to remote No front panel instrument settings are changed by the transition from remote to local but the following parameters are set Trigger State is set to freerun Average Count set to 5 Display State on When the Vector Voltmeter goes to local mode the front panel R annunciator turns off However when the Vector Voltmeter is being addressed whether in local or remote its front panel L or T annunciator remains lit Receiving the Local Lockout Message The Local Lockout message is the means by which the controller sends the Local Lockout LLO bus c
65. routine which is run whenever the instrument power is switched on This routine checks the assemblies in the HP 8508A Vector Voltmeter When the self test routine is initiated the current firmware revision will be shown in Display 2 for a few seconds Display 1 will then show tS while Display 2 shows a 3 digit number appropriate to the assembly being tested The entire test routine takes approximately 8 seconds to complete If one or more faults exist the self test routine will halt at the first fault and display the appropriate error number In this situation refer to Section 8 Troubleshooting in this manual You can perform an automatic calibration sequence by pressing SHIFT CAL TEST All other maintenance should be referred to qualified service personnel E1089 3 1 Operation an 3 4 NEW USER INTRODUCTION WARNING Before the Vector Voltmeter is switched on all protective earth terminals extension cords autotransformers and devices connected to it should be connected to a protective earth grounded socket Any interruption of the protective earth grounding will cause a potential shock hazard that could result in personal injury For continued protection against fire hazard replace the line fuse with only a 250V fuse of the same rating Do not use repaired fuses or short circuited fuse holders CAUTION Before the Vector Voltmeter is switched on it must be set to the same line voltage as the power source or damage to the in
66. rrection values can be sent to the Vector Voltmeter impedance measurements can be normalized current measurements can be saved as a reference and the normalization function can be switched on and off The default state is ali correction off CORRection DATA allows data to be sent to the Vector Voltmeter for use as a reference value A B and PHASe are used to define the destination of the reference value The ability to use specific data as reference values is a function available only from HP IB The query options return the current value CORRection IMPedance sets the impedance normalization function ON 1 sets the Vector Voltmeter to normal ize impedance measurements OFF 0 implies that impedance measurements are calculated from the current value of Input Impedance The default is OFF The query option returns 1 or 0 CORRection TERMination sets the termination standard for reflection measurements The default is SHORT The query option returns the current setting as an ASCH string CORRection PERForm sets the A B and PHASe references to be the current measurement values CORRection STATe defines if the CORRECTION function is in use It sets the normalization function to ON 1 or OFF 0 The default is OFF The query option returns 1 or 0 Direct Analog Output DANalog ONJOFF 1 0 Sets the Vector Voltmeter to operate as a simple converter The frequency and amplitude ranges are locked and the rear panel outputs represent
67. rs 2 HP 10218A 1 8 EQUIPMENT AVAILABLE FOR USE WITH THE HP 8508A A printer and controller can be used with this instrument i 4 E1059 General Information 1 9 RECOMMENDED TEST EQUIPMENT Table 1 1 lists the test equipment required for testing adjusting and servicing the Vector Voltmeter The Critical Specifications column describes the essential requirements for each piece of test equipment Other equipment can be substituted if it meets or exceeds the critical specifications Instrument Synthesized Signal Generator Power Divider DVM AC Calibrator 50 ohm Termination Dual Channel Synthesizer Attenuator Attenuator Driver RF Power Meter Power Sensor Oseilloscape Accessory Kit Input Module Extender Table 1 1 Recommended Test Equipment Critical Specification Frequency Range 100KHz to 2000MHz Output Level 604Bm to 20dBm de to 18G Hz S0ohm Insertion Loss 6dB Tracking lt 04dB Sensitivity imV Range to LOV Frequency Output of 20kHz Output Level 100mV 20uV 50 ohm Type N m SWR lt 1 01 Frequency Range 0 to 13MRHaz Output Level 104Bm to 19dBm Phase Offset 175 deg Independent adjustment on both channels for both magnitude and phase O 110dB in 10dB steps Calibration Certificate required Required for HP 84966 100kHz to 4 2GHz with Power Sensor ImW Reference Output NBS Traceable 50 ohm 100kHz to 4 2GHz SWR 1 2 1uW to 100mW Bandwidth SOMHz Sensitivity 1mY div Sw
68. s displayed Units selects the linear scale and dB selects the log scale Example 1 Amplitude of A has a units scale in mV and a dB scale in dbuV Example 2 Power in A has a units scale in uW and a dB scale in dBm FUNCTION KEYS REF Works in A amplitude B amplitude B A magutude and Phase to make measurements relative to a set of reference values SHIFT SAVE REF stores the current A B and Phase values and turns REF on When REF is turned on displayed phase measured phase saved phase and displayed measured amp or mag amplitude or magnitude saved amp or mag REFL MEAS Uses measurements of B A ratio and B A phase to make simple reflection measurements using an external device The SHORT and OPEN reference impedances are used with a bridge or directional coupler and LOAD is used when making measurements with a Tee Note that LOAD is selected as a shifted function To initialize the measurement connect the external equipment and connect the appropriate reference impedance to the test port Press SHIFT SAVE REF The REF LED is automatically turned on The A B and phase values are then retained and used as a correction for any level and or phase changes occurring between the A channel incident signal and the B channel reflected signal To make a corrected measurement connect the DUT to the test port It is also possible to make an uncorrected measurement by turning REF off When making Z or
69. s set true The query option returns 1 when all pending operations have been completed Reset lt HP1B gt RST The reset function sets the Vector Voltmeter to a front panel state the same as using the PRESET key It has no effect on the status registers or results waiting to be read Self Test TST This command initiates an instrument self test and causes a result to be output The result will be zero 0 if the test is completed without errors A one 1 indicates an error has occurred Full details of the error codes appear in the Troubleshooting section of this Manual Service Request Enable lt HP18 gt SRE lt nrf gt Sets the service request conditions Status Byte bit usage is as follows bit 4 Message Available bit 5 Standard Event Status Register summary bit bit 7 Operation Status Register summary bit Other bits are unused The query option returns the currently selected conditions E1089 9 47 Operation Standard Event Status Enable ESE lt nrf gt Sets the Standard Event Register mask conditions The query option returns the currently selected conditions Range 0 through 255 using encoding as in Table 3 2 Standard Event Status Register ESR Returns and Clears the current value of the Standard Event Status Register Status Byte Query STB Returns the current value of the Status Byte with Master Summary Status MSS as bit 6 The Byte consists of bits which summarise each Status Reporting Structure Bi
70. s to simulate key presses Each key is simulated by sending its keycode given in Table 3 3 Operation The query option returns the code of the last key pressed Table 3 3 Keycodes Keycode Descri ption A 8 REFL MEAS FORMAT POWER MEAS B A MAG B A PHASE REF SELECT REF SYSTEM IMPD METER SELECT LOCK RANGE STEP UP STEP DOWN MAG RANGE HOLD VALUE DISPLAY SHIFT LCL PRESET SYSTem FORMat sets the HP IB output format for measurement results Two formats are available ASCh and FP64 and they are described in the earlier section on HP IB Response Formats Trigger lt HPIB gt TRG The trigger command performs the same function as the Group Execute Trigger command defined by IEEE 488 1 that is it initiates a new measurement when the TRIGger SOURce is BUS Trigger Setup lt XP18 gt TRIGger Source SOURce BUS FREErun The trigger setup function allows the trigger mode to be selected In freerun the Vector Voltmeter makes measure ments as quickly as possible When the trigger source is set to BUS the Vector Voltmeter waits to receive a trigger before initiating the next measurement Wait to continue lt HP18 gt FIA This command causes the Vector Voltmeter to complete all current actions before accepting any more commands It can be used to synchronize the instrument s operation with other equipment E1039 O peration Performance Tests Performance Tests Section 4 4 1 INTRODUCTION
71. signals which can be fed to external measuring equipment There are two distinct modes of operation for these outputs Normal Mode This mode provides an analog representation of the digital display values including internal instrament correction factors OUTPUT 1 corresponds to DISPLAY 1 and OUTPUT 2 corresponds to DISPLAY2 The update rate is the same as the display update rate approximately 3 readings per second The sensitivity is ImV per displayed digit A display value of 123 4mV will produce a d c output of 1234mV A display value of 135 7 degrees will produce a de output of 1357mV If the MAG RANGE key is used to change the display resolution the rear panel outputs will change with the display values A typical use of this mode might be to drive a chart recorder or similar logging instrument Direct Analog Output Mode This mode provides continuous direct output signals from the internal magnitude and phase detectors through 800Hz low pass filters Only limited internal instrument correction factors are applied to the output signals OUT PUT 1 corresponds to either A or B magnitude in mV whichever is selected on the front panel OUTPUT 2 corresponds to B A phase The full scale deflection FSD chosen on the front panel always produces an output of 1 volt and this defines the OUTPUT 1 sensitivity A display FSD of 1000mV will produce an output of 1000mV for an input of 1000mV A display FSD of 31 6mV will produce an output of
72. strument may result E1089 Operation ATTENTION Static Sensitive Devices Don t zap your input probes The probes of the HP 8508A are susceptible to damage from electro static discharge ESD o with the following precautions to help avoid damage to your probes Anti static precautions Never touch the tip of the probe Eliminate ESD on the body by wearing a snug fitting ground strap that is connected to earth ground through a 1M ohm resistor Eliminate ESD on the work surface by using a grounded anti static bench mat Optional floor mats provide an extra measure of protection especially in areas with floor carpet Never use this product on a carpeted work surface unless the carpet is of a conductive type specifically designed to eliminate ESD Do not introduce ESD into the Device Under Test DUT while using the probes If an unprotected person touches a part of the DUT a static surge could damage the DUT as well as the probes Always refit the protective cover when the probe is not in use Mechanical abuse The tips of the probes are fragile and can break if the probe is dropped Operation 3 5 FRONT PANEL FEATURES MEWNETT ita DRAN ERDE yia aah Tet Eia Y ew can IO E LOTA pP 4 eo b y e MEAR dass PRB Rh Amen cn Folds dH el m m ER ER EG A m m Ree ch ome RENE NR RAT RR Nit Figure 3 1 Front Panel MEASUREMENT KEYS introduction The following four keys
73. ter TOdB Pad Device Under Test Figure 3 11 Transmission Test Setup 1 Connect the A and B inputs to the power splitter Set the source output level in the normal operating range of the amplifier Set the source output frequency to 50MHz Press PRESET to return the HP 8508A to a known state 2 Press B A MAG to measure the magnitude ratio Select DISPLAY dB to measure log gain Press SHIFT then SAVE REF to store the current measurement zero the display and remove splitter and input effects 3 Connect the amplifier between the splitter and the B input and measure and note the gain 4 Press SHIFT then SAVE REF to store and use this nominal gain as a reference and reset the reading to OdB 5 Increase the source output level until the HP 8508A reads 1dB The amplifier is now operating at its gain com pression point 6 Press REF to remove the reference offset Press A MAG to measure the input voltage dBuV and POWER MEAS to convert the reading to dBm Since the splitter is symmetrical the measured power at the A input will be the same as at the amplifier input to within the tracking specifications of the power splitter Operation b Reflection The measurement of small reflections in high frequency RF systems requires careful consideration At low levels reflections from the device under test can be masked by leakage signals in the measuring equipment so to make the measurement accurately you will need
74. to use a high directivity reflection bridge or directional coupler Use a short circuit as a calibration standard and measure the return loss of a precision termination Source HP38508A 50 ohm 50 ohm A Input B input Short circuit Reflected mT Device Under LJ Test Incident Directional Bridge Figure 3 12 Bridge Test Setup Source HP8s08A 50 ohm A Input 50 ohm B input incident Retiected Device Under Directional Coupler Test Figure 3 13 Coupler Test Setup 3 17 Operation 1 Connect the A and B inputs to the bridge or splitter as shown in one of the above diagrams depending on the equipment you have available Set the source power to OdBm and frequency to the test frequency 2 Connect a short circuit to the test port as the calibration standard Press PRESET to return the HP 8508A toa known state Select REFL MEAS rho angle to measure reflection coefficient 3 Select REF SELECT SHORT to use a short circuit as the calibration standard Select DISPLAY dB to measure the reflection as return loss in dB Press SHIFT then SAVE REF to store the current measurement and display a return loss of 0dB and angle O degrees 4 Remove the calibration standard and connect the termination to be measured Read the return loss directly The HP 8508A has conversions built in to allow you to read results in normalized impedance for use with Smith charts To m
75. ts are cleared by clearing the related structure Status Control lt HPIB gt STATUS Operation Status OPERation Condition Register CONDi tion Positive Transition Filter PTkansition lt nrf gt Negative Transition Filter NTRansition lt nrf gt Event Register ZEVENt Enable Mask TENABLE lt nrf gt The status command controls the setup and operation of the condition and event registers The registers are set by positive or negative transitions of the appropriate condition enabled by transition filters EVENt and CONDition return the current values of the corresponding registers ENABle selects which events latched using the Positive TRansition and Negative TRansition filters are reported in the Status Byte summary bit 7 The query option of ENABle returns O through 255 using encoding as in Table 3 2 The query options of PTRansition and NT Ransition return the current transition masks System SYSTem Error Register ERRor NUMeric STRing Key sKEY nrf gt Format FORMat ASCI if FP64 Fhe system command covers miscellaneous housekeeping and global activities in the Vector Voltmeter SYSTem ERRor returns an error code describing any error that occurs Errors are returned as either numeric responses or as a string describing the error By default a string is returned Full details of the error codes appear in the Troubleshooting section of this Manual SYSTem KEY allows direct programming of the front panel key function
76. uffer amplifier It is part of a SOMHz source assembly and has a gain of approximately 14dB Probing at the input of the amplifier the output ofthe oscillator gives a reference signal and probing at the output of the amplifier will give the amplifier gain Use the integral source as the stimulus so the amplifier will be tested under normal operating conditions Source Amplifier Figure 3 3 Test Assembly With Measurement Points 3 9 Operation Since the circuit impedance is 50 ohms and the measurements are at relatively low frequencies we can neglect the loading effects of the probe tips on the circuit response For more sensitive applications the HP 11576A 10 1 Divider or HP 10216A Isolator accessories can be used with the probes to minimize loading effects and measure ment errors Measurement details 1 Connect both probes at point JI the amplifier input in the circuit Press PRESET to return the HP 8508A to a known starting state 2 Check that the circuit under test is powered up and that the HP 85084 A UNLOCKED indicator is off Press B A MAG and B A PHASE to display vector ratio 3 Select DISPLAY dB to measure the amplifier s gain as a log ratio Press SHIFT then SAVE REF to store the reference and set the ratio displays to magnitude 0 0dB and phase 0 degrees 4 Move the B probe to point J2 the amplifier output and measure the gain and phase change Change the frequency of the oscill
77. ve the function is associated with the B signal level If only the A voltage is displayed Channel B is unused the function is associated with the A channel When the function s engaged the LED beside the key flashes to show that a reading is being held CAL TEST When CAL TEST is selected the instrument performs its power on self checks and an internal calibration cycle If an error number is displayed or if the HP 8508A continues to m a tS message refer to the Troubleshooting section in Section 8 Service METER SELECT This key is used to associate the METER with either Display 1 or Display 2 or to turn it off If phase is being displayed in Display 2 a HI or LO annunciator lights to show the meter range PROBE POWER ME This output provides 12V supplies which is sufficient to drive an HP 85024A High Frequency Probe TEST OUT This output provides a signal at approximately 1 6MHz and 150mV to allow the user to check that the HP 8508A Vector Voltmeter is operating The signal is controlled by the SHIFT CAL TEST function The LED beside the connector 1s on when the test output is enabled E1089 7 Ta 1 Operation 3 6 REAR PANEL FEATURES es peers a AORN a a FUMA TONS narco FOR LABOHATORE USE E 8 i Pr 3 5 Acc fast oR QUALIFIED SR RSOMRL cf oa des POUR USAGE EN LaRoRs Tor gPa See ee PGR PEMRSGWMEE UURI N 11 Figure 3 2 Rear Panel The Rear Panel Outputs provide de
78. y SWR RHO Y Z CORE 5 Status Byte bit usage is as follows bit 4 Message Available bit 5 Standard Event Summary Bit bit 6 Request Service Master Summary Status MSS bit 7 Operation Status Register Summary Bit Other bits are unused 6 Standard Event Status Register bit usage is as follows bit O Operation Complete bit 4 Execution Error bit 2 Query Error bit 5 Command Error bit 3 Device Error as er Other bits are unused 7 Operation Status Register bit usage is as follows bit 0 Calibrating bit3 Measuring bit 2 Ranging Unlocked bit 4 Awaiting Trigger Other bits are unused Refer to Figure 3 23 for an example of SRO enabling and handling E1089 Operation Command Reference Commands which have no parallel in local operation are described fully in this section and are indicated by the lt HP 18 gt logo in the header Commands which operate instrument functions available from the front panel are described only briefly here because full functional descriptions are given in the section describing local operation Averaging Value lt HPIB gt AVERage COUNt lt nrf gt When making measurements the Vector Voltmeter accumulates a number of internal readings and averages them to produce a result which is fed to the display and or HP IB The averaging value can be changed only via HP IB The default is 25 measurements per reading Higher values may reduce measurement variation especially with noisy signals at the c

HP 8308A User's Manual

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