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model 1805b - MHz Electronics, Inc

1. N u inns enn 3 5 Initial Powerup and eren 3 5 Mari al OperatiOn sanu ce Fiber Ne Le ORAT MET PER Ea day du 3 6 REMOTE OPERATION ise eot tet dte xe eter 3 7 TERMINATING OPERATION 3 8 THEORY OF OPERATION ce oe rat aee qx ct t e eu cub ed ee 3 8 Power Supply Motherboard Section sse nennen 3 8 Microprocessor Section enne nennen entren rennen nene nnne 3 9 RF Amplifler Section an Ricette ti eb s 3 11 Thermistor Mount Proportional Temperature Controller 3 11 Bridge Offset Sensing Circuit 3 12 RF Switching nennen 3 12 DC Substitution I nnns nnns 3 12 RE 3 13 apaku 3 13 Calibration Facto oeenn a eae ORC Dx o a aa eae 3 13 Sources of Calibration nennen nsn nnns 3 14 Calibration Factorin a uy y e rri eve aveo eene Pera ru q ERR ee Qaqa 344 SECTION IV TESTING GENERAL suwata puis ha See ei A etum ee 4 1 MAINTENANCE Pen 4 1 PET 4 1 Preventive Maintenancoe
2. Figure A 5 Important Interface Dimensions for Type TNC Class Il Connectors MIL C 39012 26 amp 27 MATING CONNECTORS Gently mate the connectors by hand taking care not to force the coupling nut at the slightest resistance It is often possible to feel whether or not the pins are mated If the coupling nut is 4 APPENDIX CARE AND HANDLING OF MICROWAVE COAXIAL ASSEMBLIES difficult to turn either the pins are not mated the coupling nut is cross threaded or one of the connectors has been damaged by excess torque Never hold a male connector coupling nut stationary while screwing a female connector into it This rotation can erode the plating and damage both the outer interface rim as well as the pin If the pins become locked serious damage can result to both the equipment and the cable assembly ENSURING PROPER CONNECTOR TORQUE OVERTORQUING Once connectors have been properly mated apply only the proper amount of torque Overtorquing damages both connectors involved Also a connector which has been damaged by overtorquing in turn damages every connector to which it is subsequently mates It usually leads to poor system performance as well Overtorque can cause Bent pins Recessed or protruding pins Recessed or protruding dielectrics Chipped plating Damaged coupling threads Coupling nut retaining ring damage Mushroomed outer interface shells Mushroomed pin shoulders HEX NUT TYPES To
3. 2 4 AM MODULATION Connector J6 a 2 5 Power Input Assembly XF1 uu uuu 2 5 Line Voltage and Fuse Selection U 2 5 PREPARATION FOR RESHIPMENT OR STORAGE sse enne nnne 2 8 RFieshipmoent 5 Lp tai dere ase cy t cec eiue dp E Roe e ER Le de e Ed uz e 2 8 io zie ob 2 9 SECTION THEORY AND OPERATION GENERAL end aste dal dae ha aie San d oe div Sua genet 3 1 OPERATION E P 3 1 GENERAL OPERATING CONSIDERATIONS na 3 2 CONTROLS AND INDICATORS shila aaa aa nnn innen 3 2 ferio 3 3 REMOTE MACAO nein 3 3 STANDBY Indicator ms eet reda eee cedo dee 3 3 POWER e ME 3 3 a RR 3 3 DC SUBSTITUTED POWER enne nennen 3 3 s n EM 3 3 BRIDGE BALANCE Meter ua ln u m a qasa 3 3 RF OFE IndiGator tuc idee tr qna O aio cdd quoa aS OE D aaa asua 3 4 FINE NULL ADJUST Control nn 3 4 COARSE NULL ADJUST 1 nnn nennen nnn nnns 3 4 ERROR cnni idco tdeo me et Fe 3 4 RF ON OFF dove nu ie 3 4 TEMPERATURE 3 4 ADDRESS e etc e este ve bd Late dais 3 4 OPERATING
4. instrument Contact to acquire any information replacement parts returning the instrument for repair Unauthorized modification can cause injury to personnel and or destruction of the instrument Operating personnel must not remove instrument covers Component replacement or adjustments MUST BE performed by qualified service personnel DO NOT operate the instrument near or in the presence of flammable gases or fumes DETAILED PRECAUTIONS The following WARNING CAUTIONS and NOTES appear throughout the text of this manual and are repeated here for emphasis N CAUTION All procedures and steps identified as be followed exactly as written and according to ESDS device handling procedures Failure to comply WILL RESULT IN ESDS damage DO NOT use a nylon bristle brush in the solvent as the bristles may dissolve and cause damage to the circuit card or component DO NOT use ultrasonic cleaning on parts or assemblies containing electrical or electronic components Compressed air used for cleaning and or drying can create airborne particles that may enter the eye Goggles faceshields should be worn DO NOT direct air stream towards self or other personnel Pressure should be restricted to a maximum of 15 psi to avoid personal injury Under no circumstances should a wire brush steel wool or abrasive compound be used on any surface Using these items will cause extensive damage to the instrument surfa
5. Attenuator RFIN RF OUT SPECTRUM ANALYZER Ls UNDER TEST 1807 foo Mount OER oe 0 01 to 18 0 GHz L Cal factor Calibration L Precision RF Output 1 mW 0 01 to 18 0 GHz Figure 1 8 Spectrum Analyzer Calibration Setup Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description 17 5 44 45 en el 18 28 46 43 cm 8 4 21 34 cm 1805B RF CONTROL UNIT 6 97 17 70 cm TST 19 22 8 8 22 35 Figure 1 9 Model 1805 Physical Dimensions 1 11 Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description Operation amp Service Manual Section Model 1805B RF Control Unit Installation and Shipment SECTION Il INSTALLATION AND SHIPMENT GENERAL This section contains information and instructions necessary to install and interface the Model 1805B RF Control Unit Included in this section are initial inspection power requirements preparation for use and shipping instructions INITIAL INSPECTION The instrument was carefully inspected both mechanically and electrically before shipment It should be free of mars or scratches and in perfect electrical order upon receipt After unpacking the instrument do not discard the shipping and packing material until the instrument has been visually inspected and it is determined that reshipment is not necessary Perform init
6. VEM MOUNT POWER AM MODULATION i SPLITTER MOUNT BIAS MOUNT RED BLAS BIAS MOUNT IEE 488 BLACK BIAS PRECISION BUS Cable BLACK RF OUTPUT TEMPERATURE CONTROL TEMPERATURE REAR CONTROL UNIT PANEL asss PLA FRONT Models 1109 1109H 1116 1117A 1119H or 1119 Figure 2 6 Precision Power Source Setup Operation amp Service Manual Section II Model 1805B RF Control Unit Installation and Shipment PC COTROLLER S S CAL SOFTWARE P N 189 31 MUST CONTAIN GPIB INTERFACE CARD amp WINDOWS 3 1 BUS Cable s ssssssssssssss P N FRONT SYNTHESIZED CW SIGNAL BNC Cable P N PANEL SOURCE 138 492 i EXT LEVEL IEEE 488 RF OUTPUT i REAR PANEL FRONT sconessesenesesenenes MUR PANEL i RFTRANSFER i mrcoNrROL FRONT CABLE STNADARD i UNIT PANEL P N 1583 1000 Model 1807A RFINPUT Cable MODULATION I TEST MOUNT z PORT BAS MOUNT i RED BIAS MOUNT IEEE 488 BIAS BUS BLACK BLACK TEMPERATURE TEMPERATURE BEAR CONTROL CONTROL PANEL bis LLLLLLLLLIIIIU 4 Figure 2 7 Precision Power Source Setup PREPARATION FOR RESHIPMENT OR STORAGE RESHIPMENT Perform the following procedures when reshipping an instrument or component NOTE DO
7. FINE NULL ADJUST CONTROL The FINE NULL ADJUST control RI is a continuously variable knob controlled potentiometer located near the upper right hand comer of the front panel This control provides a fine adjustment of the bridge balance reading on BRIDGE BALANCE meter prior to application of RF power COARSE NULL ADJUST CONTROL The COARSE NULL ADJUST control R2 is a continuously variable knob controlled potentiometer located in the right hand center portion of the front panel This control provides coarse null adjustment of the bridge balance reading on the BRIDGE BALANCE meter prior to the application of RF power ERROR INDICATOR The ERROR indicator DS3 is a red LED located near the lower right hand comer of the front panel This indicator is active only when RF power is NOT applied and when illuminated indicates either an open circuit hookup or thermistor or failure of the bridge to balance at 30 1mW RF ON OFF SWITCH The RF ON OFF switch S2 is a two position toggle switch located near the center of the front panel During manual operation placing this switch in the left ON position applies RF power activates the 1805B circuitry to subtract the chosen dc substitution power from the thermistor elements in the mount deactivates the RF OFF indicator and activates the RF ON indicator During remote IEEE 488 bus controlled operation this switch is left in the OFF position and the automatic system controller performs its funct
8. Table 1 3 Special Tools and Test Equipment TOOL EQUIPMENT NOMENCLATURE USE AND APPLICATION MODEL NUMBER Gigatronics GT9000 or Synthesized Signal Generator 0 01 18 Operational Checkout Calibration equivalent GHz 10 dBm HP3458 or equivalent Digital Voltmeter 8 1 2 digits Operational Checkout Calibration HP436 437 438 or Power Meter Operational Checkout Calibration equivalent HP8481 or equivalent Power Sensor Type N 0 01 18 GHz Operational Checkout Calibration K e Attenuator dc Checkout Calibration Weinschel 56 10 or 10 dB Fixed Attenuator 3 5mm dc Checkout Calibration equivalent 26 5 GHz SYSIIA SureCal System Windows Software Operational Checkout Calibration SureCAL Any Windows Compalible Printer Operational Checkout Calibration with GPIB interface card and Windows M 3 1 Operating System Any Windows 3 1 Compatible Printer Calibration Report Graph Test Report Printout Weinschel 1915 or Torque Wrench 14 1 inch pounds Connector Coupling Torque Type equivalent Type N N Connectors Weinschel 080 502 or Wrench 7 1 inch pounds Connector Coupling Torque equivalent SMA 3 5mm SMA 3 5 mm Connectors TEGAM 196 417 138 417 AC Extender Board Extender Board Calibration Adjustment E i 138 417 Calibration Adjustment 1 7 Operation amp Service Manual Section Model 1805B RF Control Unit Introducti
9. return any instrument or component to TEGAM without receiving prior factory authorization RMA Number Operation amp Service Manual Section Il Model 1805B RF Control Unit Installation and Shipment Use the best available packing materials to protect the instrument during reshipment When possible use original shipping container and packing materials Cover the front panel connectors with plastic connector covers Wrap instrument with sturdy paper or plastic Place all accessories cables and loose hardware into a plastic bag Place the wrapped instrument into a strong container with a layer of shock absorbing material 3 4 inch thickness to wrap around all sides of the instrument to provide a firm cushion and to prevent movement inside the container Place bag of accessories and hardware into container If shipping the instrument for service attach a tag to indicate the following Model and serial number Service required Description of malfunction Return address Authorization to conduct repairs Instrument repair authorization Thoroughly seal shipping container and mark it FRAGILE Ship to an authorized sales representative or TEGAM INC TEN TEGAM WAY GENEVA OH 44041 USA STORAGE When Model 1805B is to be stored for extended periods pack instrument into a container using procedure described above Place container into a clean dry temperature controlled location If instrumen
10. Sets RF ON and DC Substituted Power to 8 mW Sets RF ON and DC Substituted Power to 10 mW 3 7 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation TERMINATING OPERATION The following procedures may be used to terminate 1805B operation at any time under either local or remote control a Place or ensure that the RF ON OFF switch is in the OFF position b Place the POWER switch to either of the following STANDBY position if more calibrations are to be performed and avoiding the warm up period is desired Leaving it in the STANDBY position allows the temperature of the mount to remain stabilized The STANDBY indicator should illuminate the TEMPERATURE meter should stay in the green range and all other indicators should extinguish OFF position to terminate all 1805B operation All indicators should extinguish the TEMPERATURE meter should indicate zero 0 volts and the BRIDGE BALANCE meter should indicate a zero 0 mid scale reading THEORY OF OPERATION The following paragraphs contain the theory of operation for the Model 1805B RF Control Unit The following paragraphs explains the principles upon which the Model 1805B s design is based and provides a systematic explanation of the RF Control Unit s internal components and circuitry The TEGAM Model 1805B RF Control Unit combines with a temperature stabilized feedthrough thermistor mount and an RF generator to form a closed loop R
11. 10 microwatts to a high of 10 microwatts relative to a mid meter scale reference of zero 0 A 0 reference level reading on the meter indicates that the level controlled by the Model 1805B corresponds exactly to the dc substituted power level selected on the DC SUBSTITUTED POWER switch Any deviation from the selected level is read on 3 3 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation the meter as a low or high indication in microwatts In operation COARSE NULL ADJUST control and FINE NULL ADJUST control are adjusted to achieve a 0 or null reading on MI prior to application of RF power After applying RF power either manually via the RF ON OFF switch or automatically via the IEEE 488 control bus the meter should after a momentary deviation again achieve a null reading to indicate that the Model 1805B has locked on to the RF source and is applying the proper amount ofdc substituted power for calibration purposes RF OFF INDICATOR The RF OFF indicator DS1 is a green LED located in the upper right hand comer of the front panel When RF ON OFF switch is toggled to the right OFF position this indicator illuminates indicating that 30 mW dc power is supplied to the mount and the appropriate RF control signal is routed to the rear panel If the 1805B is under remote IEEE 488 bus control DS1 illuminates when the functions of RF OFF 0 have been performed by the automatic system controller
12. 5 uW Maximum accuracy is achieved by using DC power for both bias and substitution signals This instrument employs LEDs to inform the user of RF power ON OFF condition ac power on standby mount error and remote listen functions Easy to read meters are used to monitor temperature stability and bridge balance For more information on the use of the 1805B in a typical system refer to the TEGAM System Automatic Power Meter Calibration System operation and Service Manual IM 198 3 1 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation GENERAL OPERATING CONSIDERATIONS All equipment should be operated from a regulated ac supply Allow at least one hour for electronic equipment to warm up before any measurements are made When operated from a cold start the RF Transfer Standard used with the Model 1805B will require at least two hours to reach temperature stability under control of a temperature controller This is accomplished by placing the POWER switch in the STANDBY position for the first hour and a half and then the ON Position for the last half hour with the RF ON OFF switch in the OFF position During calibration runs ensure that the Model 1805B BRIDGE BALANCE meter is zeroed prior to each calibration with the RF ON OFF switch in the OFF position Temperature variations within the laboratory should be held to a minimum to avoid excessive temperature fluctuations within the sensor or
13. 30 To code a particular address set switches 1 through 5 to either ON push top of switch in or OFF push bottom of switch in to code a binary 1 or 0 respectively Notice that when the ON position is selected a red band appears in the ON position OPERATING INSTRUCTIONS The Model 1805B RF Control Unit was primarily designed as one component of the TEGAM System IIA whose purpose is to accurately transfer the calibration factors of NIST standards to feedthrough and terminating bolometer mounts thermistor mounts and power sensors The following paragraphs provides general operating instructions for the Model 1805B such as Initial Power up and checkout procedures Manual operating Instructions IEEE 488 Bus operation and a overview of using the System Windows SureCAL Software with the Model 1805B More detailed operating instruc tions and application information for the various System IIA configurations can be locat ed in the System IIA Automatic Power Meter Calibration System operation and Service Manual IMn ag Switch Number 1 2 3 45 Decimal Weight 1 2 3 4 5 Address 0 00000 1 10000 2 01000 3 11000 4 10100 E 5 101 00 z 6 01100 Note All switches are shown in the ON position 7 11100 1 ON 8 00010 0 OFF 9 10010 10 01010 Address Truth Table 20 00101 30 0 1 1 1 1 Figure 3 3 Address Switch INITIAL POWERUP AND CHECKOUT PROCEDURES After performing the installation instructions in Section II and all
14. MODULATION Connector J2 is a BNC type female connector which is located in the upper left hand corner of the rear panel Figure 2 3 The signal present at this connector is the power leveling output voltage which controls the power output level of signal generators whose power increases with a positive going signal and decreases with a negative going signal 2 3 Operation amp Service Manual Section II Model 1805B RF Control Unit Installation and Shipment AM MODULATION SSS 1 AM MODULATION Connector c cc Connector IEEE 488 BUS O A Power Input Connector J Assembly e ati lt gt EEA Figure 2 3 Model 1805B Connector Location REAR IEEE 488 INTERFACE BUS J3 Joining the Model 1805B to a system controller requires the connection of IEEE 488 control bus to the IEEE 488 INTERFACE BUS connector located on the rear panel Figure 2 3 The IEEE 488 INTERFACE BUS connector carriers program command and data signals passing between the RF Control Unit and a system controller Figure 2 4 shows the connector s contact pin numbering scheme and Table 2 1 lists the signal designator for signal present at each contact pin PIN 12 PIN 1 EEE 488 INTERFACE BUS PIN 24 PIN 13 Figure 2 4 IEEE 488 INTERFACE BUS Pin Location AM MODULATION Connector J6 Connector J6 is a BNC type connector which is located near the upper right hand corner of the rear panel The signal present at J6 is a cont
15. center lines of two connectors before actual mating Male retaining nuts contain a small amount of necessary play which may make it possible to mate the threads without the pins being properly aligned Pin misalignment can damage pins and dielectric inserts NOTE 1 ALL DIMENSIONS IN MILLIMETERS PARENTHETICAL DIMENSIONS IN INCHES ELECTRICAL MATING PLANE 050 002 MAX 000 000 MIN SY A Figure A 1 Important Interface Dimensions for Type 7 MM Precision Connectors IEEE Std 287 APPENDIX CARE AND HANDLING OF MICROWAVE COAXIAL ASSEMBLIES MALE FEMALE REFERENCE PLANE 210 _ 2 SD gU Z E SM vu q 2 mc REFERENCE PLANE Figure A 2 Important Interface Dimensions for Type 7 MM Precision Connectors IEEE Std 287 FEMALE MALE GAGING DIMENSIONS INSULATOR 002 MAX PROTRUSION 010 MAX RECESSION REFERENCE PLANE REFERENCE PLANCE INSULATOR 002 MAX PROTRUSION FIGURE A 3 IMPORTANT INTERFACE DIMENSIONS FOR TYPE CLASS II CONNECTORS MIL C 39012 16 amp 17 A 3 APPENDIX CARE AND HANDLING OF MICROWAVE COAXIAL ASSEMBLIES FEMALE MALE REF PLANE 210 MIN 230 MAX 186 MIN 206 MAX REFERENCE PLANE Figure A 4 Important Interface Dimensions for Type BNC Class Il Connectors MIL C 39012 16 amp 17 MALE FEMALE 230 MAX 210 MIN REFERENCE 206 186 MIN 22222244 E
16. current proportional to the imbalance signal This current acts to drive the mount heater to restore thermal bridge balance As the thermal bridge nears the steady state condition Q3 causes DS1 to illuminate If the mount is cold DS1 does not illuminate since the Darlington pair configuring made up by U2 2 and Q4 is not a conducting state U1 U2 responds to an imbalance signal from an overheated mount by turning off Q3 so that it does not pass current to drive the heater or DS1 Transistor Q2 and resistor R16 combine to provide circuit protection by limiting current in the event of an output short circuit Bridge Offset Sensing Circuit The bridge offset sensing circuit drives the 1805B front panel bridge balance meter by providing a total circuit gain sufficient to realize a 200 Q per division sensitivity in the front panel meter reading To achieve this instrumentation amplifier U3 senses the bridge differential and sources the amplified difference to a transconductance amplifier made up of amplifier U4 U5B and associated components The transconductance amplifier sources the meter with a current proportional to the amplified difference seen from amplifier U3 The high gain differential amplifier senses the Wheatstone bridge imbalance This circuit gives the 1805B the required gain to achieve the high sensitivity to the level ofdc bias substituted for RF levels Three operational amplifiers make up this circuit U6 senses the bridge differential a
17. incomplete and or the instrument does not function properly refer to Section and notify TEGAM POWER REQUIREMENTS TEGAM supplies a detachable power cable P N 068 21 to connect a 100 120 220 or 240 Vac 5 10 power source with a frequency between 48 to 66 Hz to the Model 1805 B To minimize shock hazard the instrument chassis must be connected to an electrical ground Using the supplied three conductor power cable ensures that the instrument can be firmly connected to the ac power source and electrical ground safety ground at a grounded power outlet Refer to Initial Setup below before applying any power to the instrument ENVIRONMENTAL REQUIREMENTS The Model 1805B operates best within its specifications at an ambient temperature of 10 to 40 C Operating beyond these limits can affect the accuracy of the instrument and damage internal circuitry RECOMMENDED OPERATING ENVIRONMENT Normal Calibration Laboratory best practice dictates that the environment should be closely controlled This will minimize errors introduced by temperature and humidity changes A nominal temperature of 23 C 73 4 F provides a good working condition A tolerance of 2 1 Operation amp Service Manual Section II Model 1805B RF Control Unit Installation and Shipment 1 C gives allowable temperature spread Controlled temperatures also stabilize the aging process of the standards is recommended that the Model 1805B and other equipment
18. instrument under test All equipment should be operated on a laboratory work bench as firm and solid as pos sible The thermistor mounts should be used on a smooth surface such as 1 8 sheet of nylon plastic to improve ease of positioning Components should be supported at prop er intervals to avoid misalignment Connectors must be properly aligned Center lines must be coaxial connector faces must be parallel and must meet neatly and firmly When the coupling nuts are engaged and the connector starts to seat the mount should be wiggled slightly as the connector is tightened to ensure accurate seating The recommended torque applied to the cou pling nut is 7 10 inch pounds BRIDGE RF ON BALANCE METER INDICATOR RT OFT INDICATOR DC SUBSTITUTED POWER SWITCH FINE NULL ADJUST CONTROL COARSE NULI POWER ON ADJUST CONTROI INDICATOR POWER SWITCH ERROR INDICATOR RF ON OFF STANDBY REMOTE SWITCH pm TEMPERATURE INDICATOR INDICATOR M Figure 3 1 Controls and Indicators Front CONTROLS AND INDICATORS The following paragraphs provide a description of all controls and indicators located on the Model 1805B Figure 3 1 shows the location of all the switches and indicators on the Model 1805B Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation LISTEN INDICATOR The LISTEN indicator DS6 is a red LED located in the bottom center of the front panel This indicat
19. is tabulated in the Table of Contents List of Illustrations and List of Tables The manual is divided into four sections listed as follows SECTION I Introduction and General Description SECTION II Installation and Shipment SECTION III Theory and Operation SECTION IV Testing Figure 1 1 RF Control Unit Model 1805B RELATED MANUALS The following manuals contain information that may be used in conjunction with this manual to operate or calibrate the RF Transfer Standard Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description Manual Title IM128 Models 1109 1109H and 1110 Coaxial Power Standards Operation and Service Manual IM198 System Automatic Power Meter Sensor Calibration System Opertion and Service Manual IM199 Model 1807A RF Transfer Standard Operation and Service Manual IM205 Models 1111 and 1116 Coaxial Power Standards Operation and Service Manual IM241 Models 1119 1119H and 1120 Coaxial Power Standards Operation and Service Manual IM245 Models 1117A 1117A and 1118 Coaxial Power Standards Operation and Service Manual IM249 Operation Manual SWR Measurement Kit P N 187 4003 IM255 Operation Manual 50 75 W Minimum Loss Matching Pad P N 138 650 IM267 Model 1727A Amplifier Operation and Service Manual CONTACTING TEGAM In the event of an instrument malfunction contact TEGAM An apparent malfunction of an instrument or component may be co
20. level cause a change in the bridge currents This change in current is called the dc substitution Without application of RF power RF OFF to the system thermistor mount dc substitution provides the current through the bridge sufficient to bias this thermistor mount at 30 mW The 200 ohm equivalent resistance of the TEGAM Model 1109 Feedthrough Mount which makes up one leg of the Wheatstone bridge dictates the 1805B s 30 mW operating point Relay K12 in this state allows the resistive section consisting of R21 and R22 to shunt the bridge circuit This causes the correct current to flow for 30 mW bias Fine and coarse adjustments to the bridge current front panel potentiometers correct small errors in the thermistor bias operating point 3 12 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation TO K THRU VO VENIE OARS NEILA AIUSTMENT R21 TO MOUNT VIA JI Figure 3 8 Simplified dc Substitution Circuit With the RF power applied to the system thermistor RF ON the mount requires less bias current to hold its operating point of 30 mW In fact by decreasing the dc bias by a known amount RF can be applied until the original operating point is again achieved The amount of RF power needed to fmd this operating point is proportional to the dc current removed The dc substitution board gets its name from this substitution ofdc power for RF power Resistive sections bias the bridge for el
21. net Cabinet or Standard Rack 1 2 Rack Mount Remote IEEE 488 1978 full function Bus Control of RF ON OFF and Substituted dc Power Levels 0 5mW and 1 10 mW in 1 mW steps Local Manual front panel control of all function such as RF ON OFF and Substituted dc Power Levels 0 5mW and 1 10 mW in 1 mW steps DC Substituted Power Level Range 0 5 1 2 3 4 5 6 7 8 9 and 10 mW DC Substituted Power Accuracy at 30 0 7 mW bias power 0 1 5 UW Bias Power Range 29 31 mW automatic with error indication for out of range balance condition Power Level Control Range Approximately 3 23 dB minimum dependent upon specific signal source Leveled RF Power Dynamic Range 3 dB Referenced to DC Substituted Power Unbalanced Detector Sensitivity 2 mW division Resolution 0 2 mW Level Control Loop Gain 80dB minimum Ambient Temperature Range 50 to 104 Loop Gain 80 dB minimum Open Loop Frequency Response 0 1 Hz Warm Up Drive saturated 8 10 V at 200 mA min Indicator Voltmeter with marked operating point Bias Power Temperature Sensitivity 2 mW C hr Mount Warm Up Time 2 hours nominal Internal Temperature 46 C nominal Related thermistor mount specifications Mount Bias Binding Post standard 0 75 spacing for Banana plugs MODULATION BNC female AM MODULATION BNC female CONTROL Temperature four pin threaded IEEE 488 INTERFACE BUS 24 pin connector per IEEE 488 1978 Recommended Materials Table 1 2 pro
22. of the System Precision Power Source INPUT OUTPUT OPTIONS The following paragraphs provide a description of the connections that can be made to the Model 1805B RF Control Unit Figures 2 2 and 2 3 show the location of these connectors Operation amp Service Manual Section Il Model 1805B RF Control Unit Installation and Shipment Sufficient power levels are present at the Power Input Assembly to cause personal injury Ensure that the Model 1805B power cord is DISCONNECTED before attempting to change fuses 18058 RF CONTROL UNIT Qr WANNA AMI MICROWATTS yo NI BRIDGE BALANCE RF O COURSE NULL ADJUST ERROR TEMPERATURE CONTROL MOUNT BIAS Para 2 2 3 2 TERMINALS Para 2 2 3 1 Figure 2 2 Model 1805B Connector Location Front MOUNT BIAS Terminals E1 and E2 These MOUNT BIAS Terminals E1 and E2 are spade lug connecting posts which are located in the lower right hand corner of the front panel Figure 2 3 Present at these connectors is the dc bias voltage to be applied to the thermistor mount Per convention red is dc whilte black is dc TEMPERATURE CONTROL Connector J1 The TEMPERATURE CONTROL Connector J1 is located near the lower right hand corner of the front panel Figure 2 2 and is a four pin threaded connector which provides the current required to control the internal temperature of the thermistor mount AM MODULATION Connector J2 The
23. substituted power and frequency levels at which variances in the stability test occurs Place all Test Equipment Power switches to ON Allow for a 3 24 hour warm up period for the Feedthrough Power Standard and Power Meter to Stabilize Zero and calibrate the power meter and sensor Set the Signal generator to a desired frequency For example if using a F 1109 select a frequency between 0 01 and 18 GHz Reset the dc substituted power level of the Model 1805B according to the value ofP and Table 4 2 Wait for stabilization and then take 10 random power readings in a one minute time period and record results Table 4 2 dc Substituted Power Setttings P T _18058 SETTING mw EIL g Verify that all power readings are within 3 uW If YES repeat step ffor all power levels listed in Table 4 2 If NO refer to the RF Amplifier Board calibration procedure If the test fails subsequent to calibration troubleshoot the board for component failures CONTACTING TEGAM Do NOT return any instrument or component to the factory without prior authorization When an instrument or component has to be returned to the factory Section provides the necessary information to contact and return the instrument or component to TEGAM Warranty Inc warrants this product to be free from defects in material and workmanship for a period of one year from date of shipment During the warranty period we will
24. support or move equipment SECURING CABLES Use toothed rubber lined P clamps to hold cables in place If it is necessary to use tie wraps use the widest possible wrap and the lowest setting on the gun to ensure the minimum pressure on the cable STORING CABLES When storing cables minimize cable set by coiling them in large diameters lor 2 feet Unroll the cable properly when it is ready to be used do not pull the loops out hastily Similarly re roll them when storing them away again CLEANING CONNECTOR INTERFACES Use the following guidelines in cleaning connector interfaces A Do not use chlorinated solvents including common tap water These solvents are E extremely penetrating and sometimes ruin otherwise good devices and assemblies Moisten a cotton swab with isopropyi alcohol Roll the swab on a paper towel to remove excess Use the moistened cotton swab to wipe away debris Do not try to dissolve the debris by overwetting the swab Repeat the cleaning process using additional swabs as necessary If metallic parti cles are embedded in the dielectric use an eyeglass and a sharp pick in an attempt to dislodge them Swab again When satisfied that the interfaces are clean blow them dry with dry compressed air or preferably dry nitrogen pressurized spray cans work well Do not use breath F Clean the mating connectors These may be the source of debris A 6
25. the power level and closed loop stability of a precision source subsystem which is composed of a signal generator a Model 1805B and a Model 1807A RF Transfer Standard or Feedthrough Thermistor Mount An amplifier will also be used in this procedure to obtain system lock at higher 1805B dc substitution power settings This test may be easily automated by use of an optional IEEE 488 bus controller and SureCAL Windows software Listed below is the necessary equipment to perform the setup Operation amp Service Manual Section IV Model 1805B RF Control Unit Testing MODEL NOMENCLATURE PC Controller with National Instruments IEEE 488 GPIB interface Any Windows Compatible Printer TEGAM SYSIIA SureCal SureCAL Windows software TEGAM 1109 Feedthrough Thermistor Mount 1807A 1116 1117A 1119 Windows Compatible Printer Any PC Controller with National Instruments IEEE 488 GPIB interface Windows Compatible Printer Windows Compatible Printer Windows Compatible Printer Printer IEEE 488 BUS Optional Source Generator TEEE 488 Controller RF Level Control Model 1805B RF Output RF Control Unit to 10dBm Model 1727 Power Meter RF Amplifier rp Eg gt Splitter Model F1109 Feedthrough Standard z PRECISION POWER SOURCE Precision RF Output 1 mW 0 01 to 18 0 GHz Figure 4 1 Closed Loop Stability Setup a Setup equipment as shown in Figure 4 1 Listed below ar
26. to change the operational power requirements to either 100 120 220 or 240 Vac Table 2 1 IEEE 488 INTERFACE BUS Signal Designators DIO 8 3 Do 5 E 8 qw LS _ 7 0 GND 7 GND 8 GND 9 3 sa X Eg e 9005 LINE VOLTAGE AND FUSE SELECTION When shipping with the U S TEGAM configures the 1805B for 120 Volt operation Overseas shipments may vary The following steps provide procedures to reconfigure the line voltage and replace the Fuse Assembly Figure 2 5 Table 2 2 lists fuse requirements for the available operational voltages Model 1805B accepts either American 0 25 x 1 250 or European bmm x 20mm fuses N WARNING Sufficient power levels are present at the Power Input Assembly to cause personal injury Ensure that the power cord is DISCONNECTED before attempting to change fuses Table 2 2 Line Voltage Fuse Requirements Operational Line Voltage Fuse Requirement TEGAM Part No 100 or 120 Volts 10 at 48 to 66 Hz 0 75 AMP Slo Blo 220 or 240 Volts 10 at 48 to 66 Hz 0 4 AMP Slo Blo AN DO NOT connect or apply power to this instrument until the Power Input Assembly has been adjusted to the operational line voltage a Disconnect the power cord from the Voltage Selector Fuse Assembly Figure 2 5 b Slide plastic window to the left and pull to the back and left on the fuse pull lever to eject the fuse c Remove the Volta
27. B and System IIA Precision Power Source can perform calibrations from 1 mW to 10 mW in the 100 kHz to 26 5 GHz frequency range Refer to the Model 1727A Operation and Service Manual for more information Figure 1 5 shows a setup to using the Model 1805B as part of the System Precision Power source and the TEGAM SWR Measurement Kit to measure Return Loss SWR The SWR Measurement Kit includes a return loss bridge with an open and short Using the System Precision Power Source the DUT s impedance to 50 ohms can be checked by measuring return loss through the return loss bridge The actual measured return loss can be readily converted into SWR by the system software Refer to the SWR Measurement Kit manual for more information Printer Optional IEEE 488 BUS RF Level Control Source Generator RF Output 10 dBm REC or Vrf OUTPUT POWER METER sesssssss SENSOR OUT mu wuncnasanss PRECISION POWER SOURCE Precision RF Output 4 mW 0 01 to 18 0 GHz Figure 1 3 Typical Coaxial Power Sensor Configuration 1 6 Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description Table 1 2 Recommended Consumable Materials ommum eB TOSS Amino Woot id IBA E e S Cloth Lint Free E Type 6 Filler Coat Adhesive EE CPC HERES 7 Permanent Polymer Coating IPC SM 840 Class Solder Mask
28. EE 488 Bus or front panel RF ON OFF switching Elimination ofac dc error by using dc for both bias and substituted power Automatic control of dc level to within 0 1 1 mW Constant dc level over an ambient temperature range of from 10 to 40 Capability to correct RF source level variations of 3 dB Internal temperature controller for controlling internal temperature of thermistor mount Physical Description Refer to Table 1 1 for all the physical dimensions for the RF Control Unit Model 1805B The RF Control Unit features a POWER ON OFF STANDBY switch indicators a TEMPERATURE control meter a RF ON OFF switch indicator DC SUBSTITUTED POWER mW control BRIDGE BALANCE meter MOUNT BIAS connectors REMOTE LISTEN ERROR indicators and FINE COARSE NULL ADJUST controls which are all located on the front panel The rear panel contains the input power connector and fuse selector assembly INPUT OUTPUT REMOTE PROGRAM connectors ADDRESS selector switch IEEE 488 INTERFACE BUS connector and AM MODULATION connectors The RF Control Unit can be easily stacked with other TEGAM instruments or mounted in any cabinet or rack designed according to EIA RS 310 and M1L STD 189 using the appropriate hardware Figure 1 2 and the following list are provided as an aid in identifying and locating modules and assemblies within the Models 1805B RF Control Unit A1 MICROPROCESSOR PC BD ASSEMBLY A2 DC SUBSTITUTION PC BD ASSEMBLY
29. F control system Figure 3 5 that achieve precise control ofdc substitution power levels At the core of this system are two thermistor beads with negative temperature coefficients whose resistances total 200 ohms when biased at 30 mW The temperature stabilized feedthrough thermistor mount power splitter contains these thermistor beads These thermistor beads whose resistance decreases as a function of increasing power compromise a leg of self correcting de biased Wheatstone bridge circuit which origi nates in the TEGAM Model 1805B RF Control Unit When a precise level ofdc bias is removed from this bridge circuit by manual or bus controlled switching of the Model 1805B an unbalance bridge condition occurs The output of this unbalanced bridge is directly related to the precise level dc bias removed After amplification and filtering the voltage output of this unbalanced bridge drives a voltage controlled attenuator This component varies the attenuation of RFpower incident upon a feedthrough thermistor mount in a manner that makes the RF power proportional to the decrease in dc bias that created the unbalanced condition Application of the attenuated RF power via one port of a power splitter restores the total 200 ohm bias to the thermistor beads and thus bridge balance The resistance of the thermistor pair is directly related to the sum ofRF power applied from one output port of the power splitter and the dc power from the bridge Since an eq
30. H 3 5 Simplified Microprocessor Block 3 9 Precision Power Source Schematic a 3 10 RF Amplifier Functional Diagram esee 3 11 Temperature Control Circuitry enne nnns 3 11 Simplified dc Substitution Circuitry enne 343 Closed Loop Stability nennen nnnm nnne 4 6 Removal and Installation LIST OF TABLES Specifications EH 1 5 Recommended Consumable Materials esee 1 7 Special Tools and Test Equipment 1 7 IEEE 488 INTERFACE BUS Signal Designators 2 5 Line Voltage Fuse Requirements U U eene nennen 2 5 Mnemonics for Remote Control n rr 3 7 INSPECTION eair eerie tie line de de det ee Pav w aa 4 3 Dc Substituted Power Settings eene 4 7 Pin Height nennen nennen enne nnne nnns A 1 Connector Torque Recommendalions eene A 5 APPENDIX A CARE and HANDLING of Microwave Coaxial Cable Assemblies Care and Handling of Assemblies
31. IEEE 488 in the form of mnemonics composed of a single ASCII character Table 3 1 lists these mnemonics and provides an explanation of each command All commands must be terminated by ASCII codes for Line Feed OA and or an EOI with the last character For more information on bus structure management and terminology refer to the IEEE Standard 488 1978 Digital Interface for Programming Instrumentation The REMOTE indicator is lit when the 1805B is placed into remote mode by the bus controller When the 1805B is addressed by the bus controller the LISTEN indicator illuminates and stays lit until another device on the bus is addressed Set the desired DC Substituted Power level using one of the mnemonics listed in Table 3 1 Monitor the 1805B s BRIDGE BALANCE meter to ensure that the signal is locked This is indicated by a momentary deflection of the BRIDGE BALANCE meter followed quickly by a return to zero indicating a locked condition If the meter deflection persists the condition There is no feedback to the bus controller that signals whether the 1805B is properly locked Table 3 1 Mnemonics for Remote Control MNEMONIC ACTION Sets RF ON and DC Substituted Power to 5 mW Sets RF ON and DC Substituted Power to 1 mW Sets RF ON and DC Substituted Power to 2 mW ets RF ON and DC Substituted Power to 3 mW p et ae Sets RF ON and DC Substituted Power to 5 mW Sets RF ON and DC Substituted Power to 6 mW
32. MODEL 1805 Control Unit Instruction Manual P N IM200 CD Rev This owner s manual was as current as possible when this product was manufactured However products are constantly being updated and improved Because of this some differences may occur between the description in this manual and the product you received TEGAM INC TEN TEGAM WAY GENEVA OH 44041 TEL 440 466 6100 FAX 440 466 6110 www tegam com Publication Date May 2007 SAFETY SUMMARY DEFINITIONS The following definitions apply to WARNINGS CAUTIONS and NOTES found throughout this manual N WARNING Highlights an operating or maintenance procedure practice statement condition etc which if not strictly observed could result in injury and or death of personnel Do not proceed beyond a WARNING symbol until all the indicated conditions have been fully understood and or met N CAUTION Highlights an operating or maintenance procedure practice statement condi tion etc which if not strictly observed could result in damage or destruction of the equipment Do not proceed beyond a CAUTION symbol until all the indicat ed conditions have been fully understood and or met NOTE Highlights an essential operating or maintenance procedure condition or statement that must be highlighted GENERAL PRECAUTIONS The following are general precautions that are not related to any specific pro cedure and therefore do n
33. POWER ASSEMBLY 4 USED A5 NOT USED A6 POWER SUPPLY MOTHER BD ASSEMBLY 1 3 Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description A7 30 V POWER SUPPLY ASSEMBLY A8 FRONT PANEL ASSEMBLY A9 REAR PANEL ASSEMBLY W1 RF CABLE ASSEMBLY W2 RF CABLE ASSEMBLY W3 ADDRESS SWITCH CABLE ASSEMBLY WA CABLE BAND SELECT ASSEMBLY XF1 INPUT POWER ASSEMBLY Specifications Table 1 1 lists specifications to be considered when using the RF Control Unit POWER SUPPLY POWER SUPPLY REAR PANEL 8 MOTHER BD ASSY ASSY INPUT POWER ASSY A5 NOT USED A4 NOT USED bs NEN 1 A2 MICROPROCESSOR A8 DC SUBSTITUTION N W3 PC BD ASSY FRONT PANEL PCBDASsy RFPOWERBD ADDRESS SWITCH ASSY ASSY CABLE ASSY Figure 1 2 Model 1805B Assembly Location 1 4 Operation amp Service Manual Model 1805B RF Control Unit Specification Temperature Range Power Requirements Physical Dimensions Figure 1 9 Construction Operating Modes DC Substitution Temperature Controller Connectors Section Introduction and General Description Table 1 1 Specifications Description Operating 10 to 40 C 50 to 104 F Storage 40 to 75 C 40 to 167 F 100 120 220 240 Vac 5 10 48 66 Hz 40 Watts nominal Depth 17 5 44 45 cm Width 8 4 21 33 cm Height 7 17 78 cm Weight 13 Ibs 5 9 kg
34. an moisture free compressed air or preferably dry nitrogen 4 2 Operation amp Service Manual Model 1805B RF Control Unit ITEM Section IV Testing Table 4 1 Inspection INSPECTION Capacitors Castings Housings Connectors Diodes Hardware Intergrated Circuits Internal Wiring Painted Surfaces Performed Packing Printed Circuit Boards Relays Resistors Switches Terminal Boards Cracked blistered or dented broken or loose seals or leads signs of leakage polarized tantalum capacitors loose or missing mountings Dents cracks scratches or other damage loose or missing handles brackets or mounting hardware damaged mounts corrosion or excessive dirt Bent broken or corroded pins Cracked or broken inserts cracked or broken shell loose or missing mounting nuts washers or screws improper saddle clamp installation Signs of overheating cracked or broken case seals or leads Stripped threads missing washers corrosion or other signs of damage Signs of overheating cracked or broken case broken seals or leads Frayed broken or abraded insulation improperly dressed or tied cables broken corroded or poorly soldered conductors at the terminals missing or damaged sleeving at connector terminals Scratches chips or peeling Nicks burrs or foreign materials present Broken or loose wires damaged circuit traces clad damaged components or chassis loose missing or damage
35. at our option either repair or replace any product that proves to be defective Inc warrants the calibration of this product for a period of one year from date of shipment During this period we will recalibrate any product that does not conform to be published accuracy specification To exercise the warranty contact Inc Ten Tegam Way Geneva Ohio 44041 phone 440 466 6100 fax 440 466 6110 M F 8 a m 5 p m ET You will be given prompt assistance and return instructions Send the instrument transportation prepaid to the indicated service facility Repairs will be made and the instrument returned transportation prepaid Repaired products are warranted for the balance of the original warranty or at least 90 days whichever is longer Limitation of Warranty Inc warranty does not apply to defects resulting from unauthorized modification or misuse of any product or part This warranty also does not apply to fuses batteries or damage from battery leakage This warranty is in lieu of all other warranties expressed or implied including any implied warranty of merchantability or fitness for a particular use TEGAM Inc shall not be liable for any indirect special or consequential damages Statemant of Calibration This instrument has been inspected and tested in accordance with specifications published by Inc The accuracy and calibration of this instrument are traceable to the Nat
36. ature for all TEGAM RF Transfer Standards The 1805B operates in a closed loop configuration for leveling the RF output of compati ble signal sources They are controlled directly using an analog signal applied to a dc coupled AM input connector Ultra stable dc high precision metal film resistors provide dc power increments across a TEGAM patented self balancing bridge The front panel bridge meter provides visual indication that closed loop stabilization has been achieved and enables rapid system operation Coarse and fine adjustments are provided to obtain a meter null reading with no RF applied In addition to the bridge balance and temperature indicator the 1805B contains several operational and performance checks front panel Mount Error indicator blinks if the voltage across the mount is not within a specified range This alerts the operator of a mount fault such as open or shorted leads or improper mount temperature DC supply voltages are monitored by PC B mounted LEDs which illuminate with an active power supply A standby mode switch allows mount heater circuit operation to maintain mount temper ature at all times This ensures full performance capability and long term stability of the bolometer mount The Model 1805B provides automatic dc level control to within 0 1 1 uW with an RF source variation of 3 dB and an ambient temperature range of 10 to 40 C The dc substitution level is held to an accuracy of 0 1
37. be supplied with power from stabilized power supplies PREPARATION FOR USE The following paragraphs provide mounting instructions Initial Setup line voltage and fuse selection and input output options for the Model 1805B RF Control Unit MOUNTING INSTRUCTIONS The RF Control Unit is shipped with four plastic feet mounted to the bottom cover This allows the user to place the instrument on any bench or to stack the Model 1805B with other TEGAM instruments When the instrument is placed on a bench or table these feet provide a level support Model 1805B can be connected to the Model 1807A or other TEGAM half rack instruments to create a 19 inch stackable bench instrument Figure 2 1 or can be mounted in any cabinet or rack according to EIA RS 310 or MIL STD 189 using Model 1919 Rack Adapter Kit Figure 2 1 Model 1805B 1807A Bench Configuration INITIAL SETUP The initial setup procedure for operating the Model 1805B RF Control Unit is as follows a Perform inspection prior to connecting the Model 1805B to any power source b Ensure the Voltage Selector Fuse Assembly is adjusted to the proper voltage setting c Check that the external power source outputs to the Model 1805 are in accordance with Table 1 1 RF Control Unit Specifications d Connect equipment using Figures 2 6 and 2 7 as a guideline Consult other instrument manuals or IM 198 for other specific connection and setup information for configuring the Model 1805B as part
38. ce NOTE DO NOT return any instrument or component to TEGAM without receiving prior factory authorization SAFETY SYMBOLS The following symbols are used to identify safety hazards found throughout this publication and or located on the instrument CAUTION HIGH VOLTAGE Caution Risk of Electrical Shcok Protective Conductor Terminal Table of Contents SAFETY SUMMARY Bina General Preautioris oi uu fev edt eU rte t HE RAM ELE EE Oe ed i Detailed Precauti ris cic accende de ete anak a ii Safety Symbols ih pe eb eet a end essct pattes zo X ii EIST OF IEEUS TRATIONS 22 22 et teda aed eae a eee LIST OF MAB E Si a eon pete eer e tb eats vi SECTION I INTRODUCTION AND GENERAL DESCRIPTION INTRODUCTION ae aite toten e Tig ev etu ti eek 1 1 PQID05622 EE 1 1 SCOP Cov ree y cd od d eo nd DECRE 1 1 Arrangetnernt e ut 1 1 Related Manuals caet ge c aset eeu tide 1 1 Gontacting 1 2 Electrostatic Discharge Sensitive sss 1 2 Abbreviations and Acronyms U 19 Safety ConsideratiOns 4 hcec dece 1 3 GENERALE DESCRIPTION 2 ride detti dere 1 3 Description Of
39. d wires cables or hardware poorly soldered connections bent or broken connector pins Damaged castings loose or missing terminals or connectors Cracked broken blistered or charred body broken or corroded leads loose or missing mountings Signs of overheating loose or broken terminals lack of positive action Cracked broken blistered or charred body broken loose or corroded leads Chassis Cleaning Clean chassis using a lint free cloth Table 1 3 moistened with water and mild detergent For harder to clean areas such as inside corners of chassis use a vacumn cleaner Connector Cleaning Where small amounts of rust corrosion and or oxide deposits are present on connectors clean externally with a soft bristle brush Table 1 3 aluminum wool or internally with an acid brush then wash with a non corrosive solvent MIL C 83102 is recommended Exercise care to ensure no metal filing or residue remains inside the connector and the connector is thoroughly dry Where rust corrosion and or oxide deposits are present in large quantities replace the connector 4 8 Operation amp Service Manual Section IV Model 1805B RF Control Unit Testing PERFORMANCE TESTING The following paragraphs provides all the necessary information to verify that the TEGAM Model 1805B is operating within its specifications as listed in Table 1 1 These tests can be used as part of an incoming quality control inspection as a periodic operatio
40. e hour for the feedthrough thermistor mount TEGAM Model 1109 to stabalize DC SUBSTITUTION ACCURACY TEST The following procedures will determine the accuracy of dc substituted power levels Using the initial test setup proceed with the following steps 4 4 Operation amp Service Manual Section IV Model 1805B RF Control Unit Testing a Obtain a reading of 1 22474 V 10 mV Ej on the DVM by adjusting the 1805B FINE NULL ADJUST R1 and COARSE NULL ADJUST R2 knobs on the right front panel b Set the 1805B RF ON OFF switch S2 located on the center of the front panel to the ON position c Turn the 1805B DC SUBSTITUTED POWER switch S3 located on the left front panel to each position 5 and 1 10 mW and record the voltage on the DVM d For each dc substituted power setting calculate the substituted power levels Ps using the following formula DF Pg mW Ej Ep2 x 103 52 e Determine that the calculated substituted power level Ps is within 0 1 of the selected DC SUBSTITUTED POWER SWITCH S3 position If the calculation is out of tolerance refer to calibration and adjustment procedures BIAS POWER RANGE TEST The following procedures will determine that the 1805B bias power range is within specification listed in Table 1 1 Using the initial test setup with the DVM connected to measure the voltage across both resistors in series proceed with the following steps a Set the 1805B RF ON OFF switch to
41. e the point to point connections Connect the RF output of the frequency generator to the input of the Model 1727A amplifier Connect the output of the amplifier to the RF IN connector of the Feedthrough Standard 1109 or 1807A Connect the 1805 s red and black MOUNT BIAS connectors E1 and E2 to the feedthrough thermistor mount s Mount Bias inputs on the 1109 J2 and J3 on the 1807A MOUNT BIAS connectors J3 and J4 Connect the 1805 s Temperature CONTROL output J1 to the Feedthrough Thermistor Mount s Temperature Control input on the 1109 link to Temperature Control connector J1 on the 1807A link to the MOUNT Heaters connector J9 4 6 Operation amp Service Manual Section IV Model 1805B RF Control Unit Testing Connect a 10 dB attenuator such as the Weinschel Model 44 10 to the RF output of the thermistor mount on the 1109 link the attenuator to its test port on the 1807A link the attenuator to its front panel TEST PORT J5 Connect the opposite end of the 10 dB attenuator to the input of a power sensor head such as the Hewlett Packard 8481 A Connect the output of the power sensor head to a power meter If desired bus the frequency source amplifier power meter and the 1805B to an IEEE 488 bus controller and control the procedure remotely If desired connect a printer to the bus controller and control the procedure remotely If desired connect a printer to the bus controller to obtain a hard copy of the dc
42. eading a level lower than actual A positive sign indicates a system that is reading a level higher than actual The true level is given by PA Pm 1 Where PA is the actual power and P is the power level as registered by the device or system under test and both are in dBm 3 15 Operation amp Service Manual Section IV Model 1805B RF Control Unit Testing SECTION IV TESTING GENERAL This section provides general maintenance practices for daily operation of the Model 1805B RF Control Unit Also included are calibration and adjustment procedures for the internal thermistor mounts and other assemblies located in the Model 1805B The sec tion provides instructions for contacting TEGAM should a problem or more information be needed MAINTENANCE The following paragraphs contain procedures outlining inspection preventive mainte nance and special cleaning instructions for the Model 1805B RF Control Unit INSPECTION Perform a visual inspection Table 4 1 in conjunction with the maintenance activities schedule when a malfunction is suspected or whenever an assembly is removed or replaced PREVENTIVE MAINTENANCE While the Model 1805B RF Control Unit requires very little preventive maintenance it should not be subjected to physical abuse severe mechanical shock high humidity or operating temperatures outside the specification range The instrument should be kept free of excessive dirt end dust since these can interfere wit
43. eading s have been taken switch the RF ON OFF switch to the OFF position and verify the the RF OFF indicator illuminates and the BRIDGE BALANCE meter momentarily deflects and then quickly returns to zero indicating a locked condition where the indicator should remain stable If the meter remains deflected to the left increase the RF level provided by the signal generator or decrease the DC Substituted Power setting If the meter remains deflected to the right decrease the RF level provided by the signal generator or increase the DC Substituted 3 6 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation Power setting If level control adjustments do not result in a lock fault isolate the problem using the system level troubleshooting procedures given in the System Automatic Power Meter Calibration System Operation and Service Manual IM 198 Failure to renull obtain lock results in inaccurate calibrations 9 For subsequent calibrations repeat Steps b through f above h When calibrations have all been completed terminate operation of the Model 1805B REMOTE OPERATION The Model 1805B can be remotely controlled over an IEEE 488 bus by a standard bus controller Connect the controller to the IEEE 488 bus interface connector located on the rear panel according to Section II Set the Model 1805B s bus address using the rear panel ADDRESS switch The Model 1805B recognizes commands sent via the
44. even different calibrated bias currents which correspond to eleven separate power substitutions Switching of one of the eleven relays K1 K11 selects the corresponding resistive sections and shunts the sections across the bridge via relay K12 The dc substitution board also contains the bridge error circuit which senses an error condition directly across the thermistor The error detection circuit is only active during the RF OFF state This circuit senses that the 30 mW operating bias point is within 7 mW by comparing the sensed potential found across the thermistor to two reference voltages These reference voltages are equivalent to those required to produce 29 3 mW and 30 7 mW across the thermistor If the thermistor fails to bias within 7 mW of the 30 mW bias point the front panel indicator illuminates CALIBRATION The following paragraphs provide theory used to perform calibration on the Model 1805B and its associated thermistor mount DC SUBSTITUTION A calibration system such as the TEGAM System IIA utilizes the principle ofdc substitution This method involves substituting a precise amount ofdc power for some amount of RF power where the two powers are proportional Thus the calibration factor K is determined by the formula PRF K the calibration factor of the mount the substituted dc power that is precisely derived and measured and PRF HF power into a matched load CALIBRATION FACTORS For a ter
45. for operation is applied to the Model 1805B and the green ON indicator is illuminated ON INDICATOR The ON indicator DS4 is a green LED located near the lower left hand comer of the front panel When the POWER switch is toggled to the ON position this indicator illuminates to indicate that all Model 1805B internal power supplies have been activated DC SUBSTITUTED POWER SWITCH The DC SUBSTITUTED POWER switch S3 is an eleven 11 position limited rotation rotary switch located in the left hand center of the front panel When the Model 1805B is under manual control this switch controls the level of the dc substituted power being supplied The selectable levels are 0 5 1 2 3 4 5 6 7 8 9 and 10 milliwatts Under IEEE 488 bus control this switch is inactive RF ON INDICATOR The RF ON indicator DS2 is a green LED located in the upper left hand comer of the Model 1805B front panel When the RF ON OFF switch is toggled to the left ON position this indictor illuminates indicating that the selected dc substituted power level is supplied to the bridge and the appropriate RF control signals are routed from the rear panel of the Model 1805B If the Model 1805B is under remote IEEE 488 bus control this indicator illuminates when the RF ON functions have been performed by the software and system controller BRIDGE BALANCE METER The BRIDGE BALANCE meter MI is located at the top center of the front panel and is scaled from a low of
46. ge Selector PC Board from the assembly by pulling it out carefully 2 5 Operation amp Service Manual Section Il Model 1805B RF Control Unit Installation and Shipment d Position the Voltage Selector PC Board so that the desired voltage appears readable right side up on the left hand side of the wafer as it faces you The X on the board in the diagram depicts this location e Slide the board back into the module as shown in the diagram with the desired volt age still appearing as set in Step d f Replace the fuse with the proper fuse according to Table 2 2 Reinsert the new fuse by placing it in the fuse brackets g Slide the Voltage Selector Fuse Assembly door shut and reconnect AC power cord Voltage Selector Fuse Fuse Assembly XF1 Voltage Selector PC Board _ x Plastic Door Figure 2 5 Voltage Selector Fuse Assembly Operation amp Service Manual Section II Model 1805B RF Control Unit Installation and Shipment PC CONTROLLER W S CAL SOFTWARE P N 189 31 MUST CONTAIN GPIB INTERFACE CARD amp WINDOWS 3 1 BUS Cable P N 1583 6 BUS Cable P N BNC Cable P N FRONT SYNTHESIZED CW SIGNAL 138 492 PANEL SOURCE EXT LEVEL IEEE 488 RF BUS J OUTPUT Wata sssssspusaspaspaqseqausasanaas 8 REAR PANEL CABLE ADAPTERS as FRONT RFCONTROL PANEL UNIT REAR
47. h in the ON position and if all indications are normal as outlined above the 1805B is ready for operation MANUAL OPERATION After the initial warm up period has been completed the Model 1805B can be operated manually under local control as follows a Leave the POWER switch in the ON position b Select the desired dc substituted power level using me DC SUBSTITUTED POWER f switch With the RF ON OFF switch in the OFF position use the COARSE NULL ADJUST control to obtain a close to zero 0 reading on the BRIDGE BALANCE meter Use the FINE NULL ADJUST control to obtain a precise zero 0 null reading on the BRIDGE BALANCE meter Switch the RF ON OFF switch to the ON position Verify the following The RF ON indicator should immediately illuminate and the RF OFF indica tor should immediately extinguish The BRIDGE BALANCE meter should momentarily deflect and then quickly revert to zero indicating a locked condition where the indicator should remain stable If the meter remains deflected to the left increase the RF level provided by the signal generator or decrease the DC Substituted Power setting If level control adjustments do not result in a lock fault isolate the problem using the system level troubleshooting procedures given in the System Automatic Power Meter Calibrator System Manual IM 198 Failure to renull obtain lock results in inaccurate calibrations After the appropriate calibration r
48. h connector functions and with normal heat dissipation Refer to Special Cleaning Instructions below The following paragraphs provide the preventive maintenance that is to be performed on the Model 1805B RF Control Unit Connectors Care should be taken to prevent strain on the interconnecting cables since damage here may not always be apparent Occasionally check the external cables and connec tors for signs of cracked insulation and or bent or worn pies Tests show that connectors must be clean for accuracy and stability This requires an inspection and cleaning of each connector immediately before use When cleaning precautions are observed regu larly connectors can maintain their stability for over several thousand connection cycles Refer to Appendix A for more information about cables and connectors Calibration Data Record Keeping a record of all the instrument and mount calibration data can provide a refer ence for periodic calibration troubleshooting of the Model 1805B after repair testing and to obtain maximum factory assistance SPECIAL CLEANING INSTRUCTIONS The cleaning procedures for Model 1805B Control Unit are divided into five general groups microwave coaxial cable assemblies circuit card and modules machined sur faces and hardware chassis cleaning and connector cleaning Table 1 3 provides a list of consumables recommended to perform these procedures Microwave Coaxial Cable Assemblies Appendix A located at the end
49. ial inspection in accordance with the following paragraphs Inspection m I Perform the following procedures before removing any item from the shipping container a Visually inspect the shipping container for any discoloration stains charring or any other signs of exposure to heat moisture or liquid chemicals b Check for any physical damage to the shipping container such as dents large snags or rips crushed sections or areas and or similar signs of excessive shock caused by careless handling Carefully remove the instrument and all other items from the shipping container Inventory all items against the packing list to ensure all items have been received e Inspect the instrument for any dents cracks deep scratches damaged or loose switches and or knobs and any other signs of careless handling eo Damage If it has been determined that shipping damage has occurred immediately contact the delivering carrier to perform an inspection and prepare a concealed damage report Do not destroy any shipping or packing material until it has been examined by an agent of the carrier Also notify TEGAM to report the nature and extent of damage to the instrument When contacting TEGAM please provide model and serial number of instrument received so that the necessary actions can be taken DO NOT return the instrument until a claim for the damages has been established If there is mechanical damage not from shipping the contents are
50. ines on pins and outer interface rims visible to the unaided eye Recessed or protruding pins It is advisable to clean the connectors prior to inspection to make subtle damage more apparent If any of the above is noted replace the assembly before its further use results in equipment damage Also inspect the mating connectors for similar damage Table A 1 provides both TEGAM specifications and MIL C39012C data for the pin height of the various types of connectors Pin height is defined as the vectorial distance along a horizontal axis of the pin shoulder from the electrical mechanical reference plane Table A 1 Pin Height Specifications MIL C 39012C FEMALE SEXLESS MIL C 39012 A BNC 2104 230_ 186 26 _ NA Sefgas Inspect the connector interface for signs of debris Debris may be in the form of Plating chips or other metal particles Dust or dirt films Other miscellaneous foreign particles A 1 APPENDIX CARE AND HANDLING OF MICROWAVE COAXIAL ASSEMBLIES If signs of debris are present clean the connector interface as directed below in Cleaning Connector Interfaces MAKING INITIAL CONNECTIONS Exercise caution when mating cables Poor connections lead to poor system performance They can also damage not only the cable assembly but more significantly front or rear panel connectors on the equipment itself which may be more difficult to repair Aligning Connectors Align the
51. ion TEMPERATURE METER The TEMPERATURE meter is located in the lower center of the front panel and provides a dc voltage analog reading of temperature and temperature stability within the thermistor chamber A green band on the meter scale provides a visual indication of normal operating temperature limits Although some mounts may cause the meter to indicate above or below this green band this does not affect the normal operation of Model 1805B if the ERROR is not illuminated and the needle is stable and does not drift or vibrate erratically ADDRESS SWITCH Remote operation of the 1805B requires settings its IEEE 488 ADDRESS switch for a unique five bit address The ADDRESS switch is located to the left of the IEEE 488 BUS connector on the rear panel Refer to Figures 3 2 amp 3 3 3 4 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation ADDRESS SWITCH E 2 eme Figure 3 2 Controls and Indicators Rear The ADDRESS switch contains seven small switches that are numbered from left to right however only switches 1 through 5 are used for selecting the unit address Switch 1 is the least significant bit LSB Addresses 0 through 30 are valid Address 31 is invalid Figure 3 3 is a view of the ADDRESS switch showing the switches numbering scheme Also included is a truth table that lists switch 1 through 5 positions 0 or 1 for addresses 1 through 10 20 and
52. ion Due to the continual scanning of the microprocessor detection of any front panel function change occurs unless the 1805B is set to remote mode in which case the microprocessor switches to a new set of instructions 8085 amp BIT MICROPROCESSOR 8255 PROGRAM MARBLE PERIPHERAL INTERFACE 3 OUTPUT DRIVERS U8 U6 Figure 3 4 Simplified Microprocessor Block Diagram 3 9 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation 488 Bus Controller MODEL 1805B MICROPROCESSOR DC SUBSTITUTION 200 Q 200 Q RF LEVEL CONTROL Feedthrough Power Standard PROPORTIONAL MOUNT TEMPERATURE CONTROL SIGNAL SOURCE TEST PORT K2 Figure 3 5 Precision Power Source Schematic In remote mode the microprocessor U1 follows remote operation instruction stored in EPROM U2 These instructions tell the processor to scan U3 the IEEE talker listener chip status register for function changes U3 is a microprocessor controlled with eight read and eight write registers that interfaces the Model 1805B to an IEEE 488 interface bus via two operation i e the processor outputs the correct bits to the driver chips to implement the required function 3 10 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation Since the microprocessor is scanning U3 the front panel is deactivated The
53. ional Institute of Standards and Technology through equipment that is calibrated at planned intervals by comparison to certified standards maintained in the Laboratories of TEGAM Inc How to Contact TEGAM TEGAM Inc Ten Tegam Way Geneva OH 44041 Phone 440 466 6100 Fax 440 466 6110 email sales tegam com 4 8 APPENDIX CARE AND HANDLING OF MICROWAVE COAXIAL ASSEMBLIES APPENDIX A CARE AND HANDLING OF MICROWAVE COAXIAL CABLE ASSEMBLIES CARE AND HANDLING OF ASSEMBLIES To ensure accurate measurements and optimal performance of TEGAM products the microwave coaxial cable assemblies used in system and test setups must be properly used and maintained Proper connections routine inspection of all cables and cleaning of the connectors are extremely important procedures which can prolong the longevity and accuracy of equipment CABLE INSPECTION Routinely check external cables for signs of cracked insulation dents twists flattening signs of jacket abrasion or other signs of abuse Wrinkles in the jacket indicate that the minimum bend radius has been exceeded Most often this occurs near the marker tubes and connectors Also inspect the connector interfaces for the following Bent pins male Bent or missing tines female Worn or chipped plating Damaged or displaced dielectric inserts Thread damage Folded or mushroomed outer interface rims Mushroomed pin shoulders male or tine ends female Score l
54. irt and dust from mechanical parts such as castings covers and other hardware proceed as follows N Compressed air used for cleaning and or drying can create airborne particles that may enter the eye Goggles faceshields should be worn Do NOT direct air stream towards self or other personnel Pressure should be restricted to a maximum 15 psi to avoid personal injury CAUTION Under no circumstances use a wire brush steel wool or abrasive compound Using these items will cause extensive damage to the instrument s surface Do NOT use nylon bristle brush in solvent as the bristles may dissolve and cause damage to the circuit card or component a Use 5 psi of clean moisture free compressed air or preferably dry nitrogen to blow loose dirt and dust from surface of item b Briskly brush isopropyl alcohol Table 1 2 onto area to be cleaned with fiber bristle brush c Remove residue with lint free cloth and repeat step b as a rinse d When parts are thoroughly clean dry parts using 5 psi of clean moisture free compressed air or preferably dry nitrogen e Clean smaller mechanical parts or hardware by dipping into a container of isopropyl alcohol Remove dirt by brushing with fiber bristle brush after parts have been immersed for several hours f Remove parts from isopropyl alcohol and rinse by immersing into a different container of isopropyl alcohol g When parts are thoroughly cleaned dry parts using 5 psi of cle
55. l Unit Introduction and General Description ABBREVIATIONS AND ACRONYMS The following list contains all abbreviations used throughout this manual Abbreviations and acronyms that are not listed conform with MIL STD 12D DUT Device Under Test ESDS Electrostatic Discharge Sensitive SAFETY CONSIDERATIONS The RF Control Unit and all related documentation must be reviewed for familiarization with safety markings and procedures before performing any operation and or service Refer to the SAFETY SUMMARY located at the beginning of this manual for a summary of safety information and procedures Following these simple safety precautions will ensure safe operation and service of the RF Control Unit GENERAL DESCRIPTION DESCRIPTION OF EQUIPMENT The following paragraphs provide a general description of the RF Control Unit shown in Figure 1 1 Functional Description The Model 1805B Control Unit is a solid state microprocessor controlled RF control unit designed for precise control ofdc substituted power When used with thermistor mounts such as the TEGAM Model 1109 1109H 1116 1117A 1119 and 1119H Feedthrough Thermistor Mounts and a stable RF generator a system is obtained which allows rapid and accurate calibration of power meter sensors and other thermistor mounts from 100 KHz to 26 5 GHz Model 1805B also provides EEE 488 Bus or front panel selection of precise dc power levels These levels are 0 5 mW and 1 10 mW in 1 mW steps E
56. mate a connector of the hex nut type al ways use a torque wrench set to the correct torque value Tighten the connector slowly until the wrench snaps Tightening too quickly can cause the wrench to exceed its set limit Do not snap the wrench more than once as this also causes overtorque KNURLED NUTS Tighten connectors with knurled nuts by hand If this does not provide sufficient tightness use hex nut connector and torque wrench instead Never use pliers to tighten a connector Table A 2 recommends torque specifications for the various types of connectors Table A 2 Connector Torque Recommendations CONNECTOR TYPE RECOMMENDED TORQUE 14 0 nls in ps Type N connector with hex nut 14 0 in Ibs 1 in lbs 7 5 lbs 305 lbs 75 inllbs 30 5 11765 PROPER CABLE HANDLING Never exceed the minimum bend radius specified for a cable Guard against tight bends at the end of connector strain relief tubing or at the ends of marker tubing where they may be less noticeable Although cable bend may seem slight the actual radius of the bend at the point of angular departure may be far smaller than the acceptable radius A 5 APPENDIX CARE AND HANDLING OF MICROWAVE COAXIAL ASSEMBLIES Never pinch crush or drop objects on cable assemblies Also do not drag a cable over sharp edges as this will pinch it and cause it to exceed the minimum bend radius Never use a cable assembly to pull a piece of equipment Cables and connectors are not designed to
57. minating mount is denoted as the measure calibration factor K4 and is the RF power from a match terminated source incident upon the mount If the mount is connected to the side arm of a coupler or a port of a power splitter for a feedthrough mount is denoted as the monitor calibration factor Ko and is the RF power emerging from the mount into a match terminated load Ppp is measured by the terminating mount as 3 13 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation Pac Y where the RF power emanating from the feedthrough mount Pac 1 the dc substituted power measured at the 1806 other instrumentation as configured Pac 2 the dc substituted power as set at the Model 1805B K2 the calibration factor for the feedthrough mount and the calibration factor for the terminating mount The system determines the calibration factor of the tested mount in terms of the known calibration factor of the previously calibrated thermistor mount and the precision measurement of the substituted dc power SOURCES OF CALIBRATION ERROR The thermistor mount power splitter combination is calibrated for K2 Since the mount calibration factor is traceable to NIST and the precise level of dc substituted power is known mismatch error accounts for the largest portion of measurement uncertainty The equation K Pdc where K the calib
58. nal check or after maintenance or service has been performed INITIAL TEST SETUP The following procedures establish the initial test setup for the Model 1805B Listed below is the necessary equipment to perform the setup MODEL NOMENCLATURE HP3458A Digital Voltmeter 8 1 2 digits TEGAM SR1 100 ohm 100 ohm Resistance Standards 2 TEGAM 1109 Feedthrough Thermistor Mount a Connect the two 100 ohm resistance standards in series and designate them Rg4 and Use the following method to obtain the dividing factor DF 1 Measure total series resistance of Rg and with a multimeter and make note of measured value 2 Measure resistance of Rgp with an ohmmeter and make note of measured value 3 Calculate the dividing factor as follows Rg1 Rs2 DF Rs2 b Connect the two resistance standards to the 1805B BIAS MOUNT terminals E1 and E2 and DVM terminals as shown below If desired link the Model 1109 Temperature CONTROL connector J1 to the 1805B Temperature CONTROL connector J1 via a temperature control cable P N 138 477 1805A RF CONTROL UNIT BRIDGE BALANCE RF NULL ON OFF ADJUST 93 CONTROL c Set 1805B RF ON OFF switch S2 located in the center of the front panel to the OFF position d Turn 1805B POWER switch S1 located on the bottom right side of the front panel to the STANDBY and ON positions ensuring that the proper LED s DS5 or DS4 illuminate Allow on
59. nd provides high gain U7 conditions signals and U8 drives the RF generator AM Modulation signal via board connector J4 and rear panel connector J2 Relay K1 forces the output signal to the maximum attenuation level assuring that the RF power always starts from a low power state when the RF power is first switched on This prevents the thermistor mount from seeing high power transients at switch points RF Switching Circuitry The board also derives the switching signals required by most RF switches The microprocessor board generates an RF ON OFF signal that enables or disables Relay K1 This relay in turn opens or closes a 5 volt loop that drives a switch in the RF generator DC SUBSTITUTION SECTION The Substitution PC Board Assembly A2 contains precision dc circuits which give the 1805B its primary accuracy These circuits have two functions dc substitution and error detection Figure 3 8 depicts a simplified schematic of the dc substitution circuit It is comprised of three legs of a resistive Wheatstone bridge whose forth leg is contained in a feedthrough thermistor mount This fourth leg containing thermistor beads links to the 1805B via board connector Jl Relay K12 allows this circuit board to operate in two states If Relay K12 is not energized the RF OFF functions operate if K12 is energized the RF ON functions operate Switching of precise resistive sections across the Wheatstone bridge according to the desired dc substitution
60. nennen riti seins 4 1 Gonner RAP mc 4 1 Galibration Data Record citi Tett a Sus eot ea ei eek a e or aL 4 1 Special Cleaning Instructions nnne 4 1 Microwave Coaxial Cable Assemblies a a 4 1 Circuit Cards and Modules a 4 1 Machined Surfaces and Hardware n a 4 2 Chassis Gleaning 2 2 u aaa oe ie oed 4 3 Connector Cleaning n 4 3 PERFORMANCE TESTING uu un lie enn Het nee ta Ho Hot Erde Ca bod ae 4 4 ESI IT e EE 4 4 DC Substitution Accuracy Test enne nennen nens nnn nen 4 4 BIAS Power Range 1 enne nennen 4 5 Temperature Control Circuit Verification sss 4 5 System Closed Loop Stability Test 4 5 CONTAGTINGTEGAM creed eun sce haces Shae eed a 4 7 3s cott ln inan c a 4 8 List of Illustrations RF Control Unit Model 1805B e re ted ds 1 1 Model 1805B Assembly e nnne enn 1 4 Typical GonfiguratiOn occ ce 1 6 10 mW Configuration Using Model 1727 nennen nennen nnns 1 8 SWR Measurement Configuration ener innen 1 8 75 Ohm Sen
61. of this manual provides all the necessary procedures for care cleaning and handling of microwave coaxial cable assemblies Circuit Cards and Modules A protective coating Table 1 3 is applied to circuit cards for protection from moisture arcing short circuiting and abrasion To remove light dirt from circuit cards and modules proceed as follows 4 1 Operation amp Service Manual Section IV Model 1805B RF Control Unit Testing N CAUTION Do NOT use a nylon bristle brush in the solvent as the bristles may dissolve and cause damage to the circuit card or component Do NOT use ultrasonic cleaning on parts or assemblies containing electrical or electronic components Do NOT bend pins of electrical connectors when using fiber bristle Table 1 2 a Briskly brush isopropyl alcohol Item 4 on Table 1 2 onto area to be cleaned with fiber bristle brush Item 1 on Table 1 2 b Carefully remove residue with clean lint free cloth Item 5 on Table 1 2 N sns Compressed air used for cleaning and or drying can create airborne particles that may enter the eye Goggles faceshields should be worn Do NOT direct air stream towards self or other personnel Pressure should be restricted to a maximum 15 psi to avoid personal injury c When parts are thoroughly clean dry parts using 5 psi of clean moisture free compressed air or preferably dry nitrogen pressured spray will work well Machined Surfaces and Hardware To remove light d
62. on and General Description MODEL 1805B RF CONTROL UNIT Printer Optional IEEE 488 TEEE 488 BUS Controller Source Generator RF Output 10 dBm Amplifier Model 1727A RF Level Control Model 1805B RF Control Unit DVM REC VRF OUTPUT Bolometric Mount SENSOR DUT PRECISION POWER SOURCE Precision RF Output 10 mW 0 01 to 18 0 GHz Figure 1 4 10 mW Configuration Using Model 1727A System Controller TEEE 488 Bus Optional RF Level Control Model 1805B RF Control Unit Bolometric Mount PRECISION POWER SOURCE 1 8S956290022222322202222235820558G52802202022005252320c222050955cc0 3 DUT Short v Circuit Circuit 50 Load COMPUTER CONTROL Power Meter SENSOR OR cinunnosMhOnenOSaMRSRURRRAREEREAS TaAMASAGAMAN ua nananbecse asway Figure 1 5 SWR Measurement Configuration 1 8 Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description Figure 1 6 shows a setup to using the Model 1805 as part of the System Precision Power source and the TEGAM 50 75 Ohm Minimum Loss Matching Pad PN 138 650 to calibrate 75 ohm power sensors over the 0 1 MHz 2 7 GHz frequency range Figure 1 7 shows the Model 1805B using a 1109H or 1119H to perform calibrations on higher power terminating sensors from 1 W to 5 W Figure 1 8 shows how a System Precision P
63. or is only illuminated when the Model 1805B is addressed as a listener via the IEEE 488 bus REMOTE INDICATOR The REMOTE indicator DS7 is a red LED located in the bottom center of the front panel This indicator is only illuminated when the Model 1805B is under IEEE 488 bus control STANDBY INDICATOR The STANDBY indicator DS5 is an amber LED located near the lower left hand comer of the front panel When the POWER switch is toggled to the STANDBY position middle position This Indicator illuminates indicating that 30 power has been applied to allow pre heating of the precision resistor network within the Model 1805B and that the 20V temperature controller circuit for the thermistor mount has been activated Ensure that input connector and voltage selector fuse assembly is set for the proper voltage before switching the POWER Switch to ON or STANDBY otherwise damage may result to internal circuitry POWER SWITCH The POWER switch SI is a three 3 position toggle switch located near the lower left hand corner of the front panel In the down or OFF position all power is removed from the Model 1805B internal and controlled external circuitry In the middle or STANDBY position 30V is applied for pre heating the internal precision resistor network 20 is applied to the temperature controller circuit for pre heating the thermistor mount and the amber STANDBY indicator is illuminated In the up or ON position all required power
64. ot appear elsewhere in this publication These are precautions that personnel must understand and apply during various phases of instrument operation or service N WARNING Potentially lethal voltages are present in this instrument Serious shock haz ards from voltages above 70 volts may exist in any connector chassis or cir cuit board Observe the following precautions Use the buddy system any time work involving active high voltage components is required Turn OFF the power before making breaking any electrical connection Regard any exposed connector terminal board or circuit board as a possible shock hazard DO NOT replace any component or module with power applied If test conditions to live equipment are required ground the test equipment before probing the voltage or signal to be tested Personnel working with or near high voltage should be familiar with modem methods ofresuscitation DO NOT wear jewelry rings bracelets metal watches and or neck chains while working on exposed equipment Be very cautious about using hand tools near exposed backplanes bus bars and or power supply terminals Use properly insulated tools When making test connections to the power supply terminals and bus bars use only insulated probe tips Verify that the instrument is set to match the available line voltage and the correct fuse is installed DO NOT install substitute parts or perform any unauthorized modification to this
65. ower Source using the Model 1805B can be configured with a Weinschel Model 8300 2 Programmable Attenuator to perform reference verification over the 0 01 18 GHz frequency range 488 Bus ss COMPUTER CONTROL RF Level Control 50 750 Matching DVM P N 138 650 Output Model 1805 RF Control Unit J Temp Bolometric Mount 75 SENSOR REC or Vnr Output 750 Precision RF Output A dois tip EN OEE 8 7 dBm to 4 3 dBm 0 1 2 7 MHz Figure 1 6 75 Ohm Sensor Calibration Setup System Controller Optional 488 Bus COMPUTER CONTROL Amplifier posssesssssassas SENSOR OR MOUNT Model 1805 BIAS RF Control Unit Power Meter 1109H 1119H Bolometer Mount Feedthru Mount Temp z Control 10 dB Splitter PRECISION Attenuator I OUTPUT 5 100mW Figure 1 7 Typical Higher Power Calibration Setup 1 9 Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description z PRECISION POWER SOURCE Printer Optional IEEE 488 BUS wass IEEE 488 Controller RF Level Control Model 1805B RF Control Unit Source Generator RF Output 10 dBm MODEL 8300 2
66. ration factor for the device under test Pac the dc substituted power as measured at the 1806 or other instrumentation as configured and Po the RF power available for calibration is defined when the equivalent source impedance is an exact 50 ohms For an imperfect source the measured incident power is defined by the formula Po Pinc I Torg P where Pinc actual effective power incident upon the device under test Po measured power available to the device under test Tg the reflection coefficient of the source and the reflection coefficient of the load CALIBRATION FACTOR IN dB When transferring calibration to an active device it is also an alternative practice to define the device calibration factor in dB rather than in 96 In this case the basic equation becomes Ky gp 10log 1dB P where the calibration factor of device under test dB the power level registered the device system under test and RF power into matched load 3 14 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation Note that with active devices such as spectrum analyzers no absolute accuracy device or system is used e g dc substitution thermistors etc so that uncalibrated power measurement values can be quite arbitrary The calibration factor can thus be up to several dB and have either sign A negative sign indicates a system that is r
67. rature Controller The thermistor mount temperature controller senses the imbalance of a thermal bridge and drives the mount heater in proportion to the imbalance signal to compensate for temperature variations This board also controls two indicators The first of these two indicators is temperature meter M2 which is located in the center of the front panel Figure 3 1 The green band on this meter indicates the proper operating temperature range The second is the light emitting diode DS1 located internally on the RF Amplifier board that indicates a near steady state temperature condition Figure 3 7 presents a simplified schematic of the termistor mount temperature controller circuitry Figure 3 7 Temperature Control Circuitry 3 11 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation U1 a high gain amplifier with excellent offset drift characteristics senses the imbalance of a thermal bridge located in the temperature stabilized feedthrough thermistor mount via pins 2 and 3 of board connector J5 This thermal bridge which is composed of two types of resistance with differing temperature coefficients balances at approximately 60 C U1 U2 interaction provides a vary ing response to the thermal bridge imbalance signal according to the relationship between the voltage differential inputs U1 U2 amplifies an imbalance signal from a cold thermal bridge that forces the series pass transistor Q3 to pass a
68. refore switching front panel controls does not cause a functional change by the unit Once in the remote mode US handles all bus protocol If the external controller requires status information U3 asks the microprocessor for the instruments status The processor informs U3 of its current status which U3 outputs to the external controller An addressing scheme allows multiple instrument control on the same IEEE 488 bus Each instrument has its own unique address U3 decodes the IEEE addresses sent by the common bus until it sees its unique adddress which tells it the information to follow is for that unit U3 fetches its unique address from the I O portion of the dual purpose EPROM I O chip U2 RF AMPLIFIER SECTION The RF Amplifier PC Board Assembly A3 functionally depicted in Figure 3 6 contains two circuits that are instrumental in closed loop leveling in the RF ON mode These circuits are a thermistor temperature controller and a bridge sense high gain differential amplifier RF amplifier board circuitry also provides RF switching according to RF ON OFF signals from the microprocessor board and bridge offset sensing that drives the front panel bridge balance meter Microprocessor Amplifier assembly 2 RF ON OFF to Sweeper AM Modulation to Generator Wheatstone Bridge Bridge Balance Mount Meter Temperature Meter Figure 3 6 RF Amplifier Functional Diagram Thermistor Mount Proportional Tempe
69. rol voltage which provides RF level control to signal generators whose power output decreases with positive going signal and increased with negative going signal THIS OUTPUT WILL NOT FUNCTION CORRECTLY IF AM OUTPUT IS CONNECTED TOALOAD Power Input Assembly XF1 The Power Input Assembly contains a three prong ac power input connector and a voltage selector fuse assembly Figure 2 3 The design of the Power Input Assembly prevents access to the Voltage Selector PC Board or the Fuse Assembly while an ac power cord is connected to the instrument This design is not to be modified The AC Power Connector located on the left side of XF1 Figure 2 3 is a plug type prong insert connector with three conductors for connection of the power cord P N 068 21 to the Power Supply Assembly located within the instrument This connector also grounds the chassis when the AC power cord is connected to a grounded wall outlet If necessary use a three prong to two prong adapter and connect the adapter s ground lead to the outlet plate retaining screw The voltage Selector Fuse Assembly on the right side of XF1 reconfigures the RF Control Unit to different operating voltages This assembly contains a line voltage fuse and voltage selector PC board Refer to following paragraph for replacement of the fuse and or proper alignment of 2 4 Operation amp Service Manual Section II Model 1805B RF Control Unit Installation and Shipment the voltage selector drum
70. rrected over the phone by contacting TEGAM DO NOT send the instrument or component back to the factory without prior authoriza tion When it is necessary to return an item state the symptoms or problems catalog and type number of the instrument or component serial number of the item and date of original purchase Also write the company name your name and phone number on an index card Then attach the card to the instrument or component to be returned Or contact TEGAM using the following TEGAM INC 800 666 1010 toll free TEN TEGAM WAY 440 466 6100 phone GENEVA OH 44041 USA 440 466 6110 fax ELECTROSTATIC DISCHARGE SENSITIVE The equipment documented in this manual contains certain Electrostatic Discharge Sensitive ESDS components or parts Therefore certain procedures steps are identified by the use of the symbol This symbol is used in two ways N CAUTION All procedures and or steps identified as must be followed exactly as written and according to ESDS device handling procedures Failure to comply WILL RESULT IN ESDS damage a When the ESDS symbo icy is placed between a paragraph number and title all of that paragraph including all subparagraphs is considered an ESDS device handling procedure b When the ESDS symbol is placed between a procedure step number and the text all of that procedure is considered an ESDS device handling procedure 1 2 Operation amp Service Manual Section Model 1805B RF Contro
71. sese A 1 Cable 1 Making Initial Connections L A 2 Aligning Conhectots 2 cer er dde ees A 2 Matirig GConrnectOrs aiio e ive eue eu ae eens 4 Ensuring Proper Connector Torque enne enne A 5 e 5 5 Knurled Nuts e ete ina e eo ee exe Pone ca e Led A 5 Proper Cable Handling eese eene entente nennen entren A 5 Securing Gables nie t ale a p ee LE de au d dE dp ee Pag veda A 6 Storirig KOTNO AAEE AT aer uui RR LR ua A 6 Cleaning Connector Interfaces a A 6 vi Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description SECTION INTRODUCTION AND GENERAL DESCRIPTION INTRODUCTION PURPOSE This manual provides Operation and Service instructions necessary to install service test and operate the TEGAM Model 1805B RF Control Unit P N 138 415 1 SCOPE This manual is to be used in conjunction with the operation and maintenance of the RF Control Unit The manual also provides a description of each assembly testing of the unit maintenance procedures to maintain the instrument ARRANGEMENT The information contained in this manual
72. sor Calibration Setup esses ener 1 9 Typical Higher Power Calibration Setup nnne 1 9 Spectrum Analyzer Calibration Setup nennen 1 10 Physical Dimensions iet te la eel oe ell aaa Dee 1 11 Model 1805B 1807A Bench Configuration sse enne 2 2 Model 1805B Connector Location 1 nennen enne nens 2 8 Model 1805B Connector Location 1 seen nennen nens 2 4 IEEE 488 INTERFACE BUS Pin Location esses enne nnne 2 4 Voltage Selector Fuse Assembly enne enne nnne ennt enn 2 6 Precision Power Source esent 2 7 Precision Power Source nas 2 8 Controls and Indicators FRONT nennen nennen enne nennen nennen entren 3 2 Controls and Indicators 3 5 Important Interface Dimensions Type 7 1 eee nennen nnnm A 2 Important Interface Dimensions Type 2mm nennen eren A 3 Important Interface Dimensions Type nennen nennen A 3 Important Interface Dimensions Type BNC n A 4 Important Interface Dimensions Type BNC n u A 4 Address SWIIG
73. system cabling has been connected as desired apply power to the 1805B as follows 3 5 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation a b C f Read over the General Operating Considerations before proceeding Ensure that the RF ON OFF switch is in the OFF position Place the POWER switch in the STANDBY position The amber STANDBY indicator should illuminate After 1 and 1 2 hours of warm up time ensure that the TEMPERATURE meter is in the green range and the meter needle is stable Place the POWER switch in the ON position Verify the following The STANDBY indicator should extinguish the ON indicator and RF OFF should be illuminated The BRIDGE BALANCE meter will register a slight deflection the TEMPERATURE meter should remain unchanged in the green range and the ERROR indicator should NOT illuminate NOTE If the ERROR indicator illuminates attempt to obtain a null reading on the BRIDGE BALANCE meter using the COARSE and FINE NULL ADJUST con trols If the ERROR indication persists then return the POWER switch to the STANDBY position and check system cabling and thermistor continuity If after performing these checks subsequent power application continues to result in an ERROR indication power should be removed from the system and the Model 1805B removed for troubleshooting After the system has had the additional 1 2 hour of warm up with the POWER switc
74. t is to stored in excess of 90 days place desiccant with items before sealing container The safe environmental limits for storage of Model 1805B are as follows Temperature 40 to 75 C 40 to 167 Humidity less than 9596 Altitude less than 40 000 12 192m Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation SECTION THEORY amp OPERTION GENERAL This section contains all the theory and operating instructions necessary to perform power measurements and calibrations using the Model 1805B RF Control Unit OPERATION The primary purpose of the Model 1805B RF Control Unit is to provide fast reliable and accurate leveled RF power when used in a closed loop feedback arrangement The unit provides automatic dc substitution at 0 5 mW and 1 mW to 10 mW in 1 mW steps using local or IEEE 488 bus control for easy and accurate transfer of calibration factors When used with the TEGAM Model 1109 RF power standard the 1805B permits the accurate transfer of up to 132 calibration frequencies traceable to NIST from 0 01 to 18 0 GHz The 1805B is also compatible with other TEGAM System components including the 1109H 1116 1117 1119 and 1119H series RF Transfer Standards refer to applicable mount manual for specifications An internal temperature controller raises and maintains the temperature of the mount chamber above ambient This minimizes the effects of changes in ambient temper
75. the OFF position Set the 1805B FINE NULL ADJUST R1 and COARSE NULL ADJUST R2 knobs fully clockwise and record the DVM reading E1 b Set the FINE NULL ADJUST R1 and COARSE NULL ADJUST R2 knobs fully c Calculate the bias range using the following formula E2 Ey and P BIASMAX Q 200Q d Ensure that the calculated bias power range meets specifications i e the minimum bias power is less than 29 mW and the maximum bias power is greater than 31 mW An out of range condition should light the front panel ERROR indicator DS3 and indicates a need for calibration P BIASMIN TEMPERATURE CONTROL CIRCUIT VERIFICATION To verify the performance of the 1805B temperature control circuit monitor the TEMPERATURE Control Meter M2 located on the lower center of the front panel When a cold thermistor mount is first connected to the 1805B and the 1805B is in POWER STANDBY mode the needle of the TEMPERATURE Control Meter should provide an approximate full scale reading 9 2 to 10 2 Once the mount has been heated by the 1805B s temperature controller for a period of one hour the needle should not vibrate and should remain well within the green shaded area of the TEMPERATURE Control Meter If the TEMPERATURE Control Meter fails to perform as indicated the temperature control circuit requires adjustment CLOSED LOOP STABILITY TEST The following provides a step by step procedure to check the Model 1805B s ability to control
76. tion form either the front panel local control or the rear panel IEEE 488 bus interface remote control The board decodes this control information and performs the tasks needed to implement the control function The 1805B s functions include switching of the substitution levels to eleven pos sible settings and the control of the RF ON OFF switching The heart of the microprocessor board is Ut an INTEL eight byte 8085 parallel microprocessor with a 6 MHz clock U1 interprets instructions stored in EPROM erasable electrically program mable ROM U10 Programmable logic array U9 interfaces the microprocessor to the program memory U10 as well as providing I O port capability Serial EPROM U1 1 contains the instru ment program for U9 which is loaded at instrument power up These instructions in program memory U10 guide the microprocessor in its operation through two main modes local and remote operation In local mode the user programs the instrument by switching front panel con trols that switch status receivers that are part of 1 0 chip U7 The program instructions stored in EPROM U2 continuously update these status receivers which are scanned by the microprocessor to derive local mode instructions If the front panel status changes the micro processor outputs the proper bits to the board drivers through the output latches ofU7 or U9 The board drivers U8 and U6 energize the relays associated with the 1805B circuits responsi ble for this funct
77. uA aaa wana eene nennen nennen tenen nni 1 3 Functional Description enne nennen nnns 1 3 Physical Descriptiorni 1 3 a E EATE hu a TS 1 4 Recommended Materials U U 1 5 Special Tools and Test Equipment 1 5 APPLIGATIONS E 1 5 SECTION II INSTALLATION AND SHIPMENT ade d ite d 2 1 Initial Inspection ec ciao i rni ru s a tn EL na dit 2 1 e rer De LR 2 1 aa hawk deen ene 2 1 Power Hedquiremoents tete th estes ete tnu dee eee 2 1 Environmental Requirements U U 2 1 Recommended Operating Environment sse 2 1 PREPARATION FOR USE 5 2 itp tee tiat be er D aude teg o eue dc ee EE a nee 2 2 Mounting INStructons rei M idi esed iae ba siot tabe tics 2 2 Inu 2 2 Input Output Options nnne 2 2 MOUNT BIAS Terminals E1 and 2 2 3 TEMPERATURE CONTROL Connector 1 2 3 AM MODULATION Connector 42 nnne 2 3 IEEE 488 INTERFACE BUS J3 2 4 REMOTE PROGRAM INPUT Connector J4
78. ual RF power level is present at the second output port of the power splitter this port sources a precision level ofRF power The Model 1805B primarily consists of four circuit groups consisting of a Motherboard Power Supply Section a Microprocessor Section a DC Substitution Section and a RF Amplifier Section POWER SUPPLYMVIOTHERBOARD SECTION The input power source is routed through the Power Entry Module Assembly XF1 before being applied to the Power Supply Motherboard Assembly The Power Entry Module Assembly allows the user to select between the two operational voltage ranges that can be accepted by the Power SupplyVMotherboard Assembly A6 This Power Supply Motherboard 3 8 Operation amp Service Manual Section Model 1805B RF Control Unit Theory amp Operation Assembly A6 provides 20 2V 5 0 5V and 15V 2V outputs to all the Model 1805 Assemblies connected to the Motherboard section of this assembly The 30V for the DG Substitution PC Board Assembly A2 is generated by the 30 V Power Supply Assembly A7 The 30 V Power Supply Assembly receives its operational power from the T1 Transformer located on the Power Supply Motherboard Assembly A6 A front panel POWER ON DS1 and STANDBY DS5 indicator is provided to allow the user to verify that an external power source is applied to the Model 1805B MICROPROCESSOR SECTION The microprocessor board functionally depicted in Figure 3 5 reads control informa
79. vides a list of recommended consumables to be used when cleaning or servicing the RF Control Unit Special Tools and Test Equipment All recommended special tools and test equipment to be used with the RF Control Unit are listed in Table 1 3 APPLICATIONS The primary function of the Model 1805B is to function as part of the TEGAM System Precision Power Source for the transfer of calibration factors to power meter sensors Figure 1 5 Operation amp Service Manual Section Model 1805B RF Control Unit Introduction and General Description 1 3 shows a typical configuration for calibrating coaxial power sensors Using other TEGAM Coaxial Feedthrough mounts and the appropriate generator an operator can easily calibrate other power sensors with frequency ranges as follows Model 1109 0 01 18 GHz Model 1116 100kHz 100MHz Model 1117 0 05 GHz 26 5 Ghz Model 1119 100 kHz 4 2 GHz However the Model 1805B can be used in many other System IIA applications such as comparing power standards spectrum analyzer calibration and to measure effects of noise on linearity at low signal levels Virtually any application requiring a precision leveled power source is a prime candidate for the Model 1805B and the System IIA The following paragraphs outline several applications for System Figure 1 4 shows a calibration setup using a TEGAM Model 1727A RF Amplifier and a 10 dBm RF Signal source to increase the output power so that the Model 1805

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