Keysight 8478B Operating And Service Manual
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Keysight 8478B Operating And Service Manual

Keysight 8478B Operating And Service Manual

Thermistor mount
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Keysight 8478B
Thermistor Mount
Operating and
Service Manual

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Summary of Contents for Keysight 8478B

  • Page 1 Keysight 8478B Thermistor Mount Operating and Service Manual...
  • Page 2 Software. The EULA and the license CONTAINED HEREIN. SHOULD governed by United States and set forth therein, does not require or KEYSIGHT AND THE USER HAVE A international copyright laws. permit, among other things, that SEPARATE WRITTEN AGREEMENT Manual Part Number...

  • Page 3: Certification

    Keysight shall not be liable for errors or for incidental or consequential damages in connection with the furnishing, use, or performance of this document or any information contained herein.

  • Page 4: Limitation Of Warranty

    Buyer. Keysight does not warrant the Buyer’s circuitry or malfunctions of Keysight products that result from the Buyer’s circuitry. In addition, Keysight does not warrant any damage that occurs as a result of the Buyer’s circuit or any defects that result from Buyer-supplied products.

  • Page 5: Waste Electrical And Electronic Equipment (Weee) Directive 2002/96/Ec

    “Monitoring and Control Instrument” product. The affixed product label is as shown below. Do not dispose in domestic household waste. Sales and Technical Support To contact Keysight for sales and technical support, refer to the support links on the following Keysight websites: • www.keysight.com/find/powersensors...
  • Page 6 Certification Sales and Technical Support Keysight 8478B Thermistor Mount...

  • Page 7: Table Of Contents

    Thermoelectric Effect Error Correction for 8478B/431 Combination ....23 Thermoelectric Error for 8478B/432 Combination ......24...
  • Page 8 CHANGE C ..............47 Keysight 8478B Operating and Service Manual...

  • Page 9: General Information

    Keysight 8478B Thermistor Mount Operating and Service Manual 1 General Information Introduction Specifications Instruments Covered By Manual Incoming Inspection This chapter contains information about initial inspection and overview of the Keysight 8478B Thermistor Mount.

  • Page 10: Introduction

    General Information Introduction Introduction The Keysight Model 8478B Coaxial Thermistor Mount is designed for use with Keysight Model 431 and 432 Power Meters to measure microwave power from 1μW to 10mW. Design of the mount minimizes adverse effects from environmental temperature changes during measurement. For increased measurement accuracy, Effective Efficiency and Calibration Factor are measured for each mount at selected frequencies across the operating range;...

  • Page 11: Incoming Inspection

    To check thermistor match, proceed as described in “Performance Tests” on page If any damage is found, inform the carrier and your nearest Keysight sales and Service office immediately. Keysight 8478B Thermistor Mount...
  • Page 12 General Information Incoming Inspection Keysight 8478B Thermistor Mount...
  • Page 13 Keysight 8478B Thermistor Mount Operating and Service Manual 2 Operation Precautions Specifications Drift Precaution Zero Set Mount Calibration Calibration Data Application Thermoelectric Effect This chapter contains information about specifications and operation of the Keysight 8478B Thermistor Mount.

  • Page 14: Operation

    Biasing Thermistors Before connecting the 8478B to a 431C or 432-series Power Meter, set the MOUNT RES switch to the 200Ω position. For Mounts with serial numbers prefixed below 1833A, set the MOUNT RES switch to 200Ω BAL (431) or 200Ω...

  • Page 15: Specifications

    Operating Resistance: 200 ohms, unbalanced Power Range with Model 432: 1μ W to 10mW Maximum Peak Power: 200W Maximum Average Power: 30mW Maximum Energy per Pulse: 10W-μs for a PRF ≥1kHz; 5W-μs for a PRF <1kHz Keysight 8478B Thermistor Mount...
  • Page 16 Stainless steel type N male (APC-7 also available- see Option 11 below). Output Connector: Mates with power meter cable (operates directly with 432). Weight: Net 140g (5 oz). Option 11: 8478B Thermistor Mount supplied with APC-7 RF connector. Keysight 8478B Thermistor Mount...

  • Page 17: Maximum Input

    1) average power, 2) pulse energy, and 3) peak pulse power. Excessive input can permanently damage the Model 8478B by altering the match between the RF and compensation thermistors (resulting in excessive drift or zero shift) or cause error in indicated power.
  • Page 18 Square-wave modulation is a special case of pulse modulation, and maximum power meter reading versus square-wave frequency is illustrated in Figure 2-4. This figure also holds for sinewave modulation. Figure 2-4 Maximum Power Meter Reading vs Square and Sine-Wave Frequency Keysight 8478B Thermistor Mount...

  • Page 19: Drift Precaution

    Let the power sensor warm up at least 30 min before perform COARSE and FINE ZERO. Operation with 431A/B/C or 430 Power Meters If the 8478B is used with a 430 Power Meter, a Model 11528A Adapter is required. Because the mount is unbalanced, a large amount of 10kHz audio bias signal may be coupled from the power meter to the RF source output.

  • Page 20: Zero Set

    RF source for the power measurement. 8478B/432 When it is inconvenient to turn the RF power off while using the 8478B/ 432 combination simply remove the mount from the source, and using the COARSE and FINE ZERO, zero the 432.

  • Page 21: Mount Calibration

    Operation Mount Calibration Mount Calibration The calibration points imprinted on the label of each 8478B allow power measurements to be made with increased accuracy. Values of Calibration Factor and Effective Efficiency are given at seven frequencies between 10MHz and 18GHz. The mounts are tested on a swept-frequency basis to assure accurate interpolation between calibration points.

  • Page 22: Calibration Data Application

    Calibration Data Application When the 8478B is used with the Model 431 or 432 Power Meters, Calibration Factor or Effective Efficiency corrections can be made by setting a front panel switch. With the proper setting, the 431 or 432 compensates for the Calibration Factor or Effective Efficiency in the 8478B.

  • Page 23: Thermoelectric Effect

    0.1µW on the 0.01mW range. Refer to “Specifications” on page Thermoelectric Effect Error Correction for 8478B/431 Combination Use the following technique to correct for thermoelectric effect error. 1. Measure power. 2. Connect a HP Model 8402B Power Meter Calibrator to the power meter DC CALIBRATION AND SUBSTITUTION connector.

  • Page 24: Thermoelectric Error For 8478B/432 Combination

    Power - - - - - - - - - - - - - - - Thermoelectric Error for 8478B/432 Combination The thermoelectric errors present in the 431 are minimized in the 432 since the thermoelectric voltage is negligible compared with the dc voltage used to bias the thermistor bridges.
  • Page 25 Keysight 8478B Thermistor Mount Operating and Service Manual 3 Operating Principles General Operation This chapter contains information about operating principles and general operation of the Keysight 8478B Thermistor Mount.

  • Page 26: Operating Principles General Operation

    RF power. Operation with 431 Power Meter The RF detection bridge balance is affected by RF power input to the 8478B, and the bridge is balanced by the application of 10kHz audio bias power. The compensation and metering bridge is indirectly, but equally affected, by the application of RF power.

  • Page 27: 432 Power Detection

    2. heat from the same environment As “D” and “C” are matched thermally, the total amounts of heat applied to reduce their series resistance equally must be equal. Figure 3-1 8478B Connected to a 432A Power Meter Keysight 8478B Thermistor Mount...

  • Page 28: 431 Power Meter Detector

    3. heat from the same environment As “D” and “C” are matched thermally, the total amounts of heat applied to reduce their series resistance equally must be equal. Figure 3-2 8478B Connected to a 431C Power Meter Keysight 8478B Thermistor Mount...
  • Page 29 Keysight 8478B Thermistor Mount Operating and Service Manual 4 Maintenance Mechanical Shock Performance Tests Troubleshooting Thermistor Compensation Repair and Recalibration This chapter contains information about maintenance and troubleshooting of the Keysight 8478B Thermistor Mount.

  • Page 30: Maintenance

    Maintenance Mechanical Shock Mechanical Shock The Model 8478B is a precision instrument. A void dropping or other mechanical shocks. Such shocks destroy the resistive match between thermistor elements, or otherwise degrade performance. Test equipment and accessories required to perform maintenance are listed in Table 4-1.
  • Page 31 Resolution: 4 significant digits Accuracy: ±0.05% Power Supply Output Voltage: 29 Vdc 6217A Cables 1.Coax-Type N connectors 11500A 2. BNC-BNC - male connectors 10502A Battery Voltage +2.0 to 3.1 Vdc “Thermistor Resistive Match Test” Resistor 2.2K ohm 5% 0698-4262 Keysight 8478B Thermistor Mount...

  • Page 32: Performance Tests

    4-1. Make sure all connections are secured tightly. 2. Set the instrument controls as follows: 8690B/8692A SWEEP SELECTOR: FUNCTION: START/STOP ALC: AMPLITUDE MOD: INT SQ WAVE START/CW: 8GHz POWER LEVEL: Adjust to maximum with the UNLEVELED light Keysight 8478B Thermistor Mount...
  • Page 33 415E. The SWR at 8GHz should be less than 1.35:1. HP 415E (8GHz)_________<1.35:1 9. Repeat steps 1 through 8 to determine the SWR at 12.4GHz. The SWR at 12.4GHz should be less than 1.35:1. HP 415E (12.4 GHz) _________<1.35:1 Keysight 8478B Thermistor Mount...

  • Page 34: Swr Measurement, 15 And 18Ghz

    15GHz should be 1.6:1 maximum. HP 415E (15GHz)________l.6:1 maximum 3. Move the 8690B START/CW control to 18GHz. Repeat steps 1 through 8 to determine the SWR at 18GHz. The SWR should be 1.6:1 maximum. HP 415E (18GHz)________1.6:1 maximum. Keysight 8478B Thermistor Mount...

  • Page 35: Thermistor Resistive Match Test

    RESISTOR (2.2K ±5%): HP 0698-4262 The small battery connected in series with the DVM is in opposition to the power supply. The value of this reverse voltage should be selected to provide voltmeter resolution of 0.001 volt. Keysight 8478B Thermistor Mount...
  • Page 36 4. Connect point A to pin 1 of the thermistor mount jack and point B to pin 2 of the thermistor mount jack. 5. Record the DVM Reading. 3466A_____________ 6. Thermistor match (±0.5Ω) is satisfactory if the two readings do not differ by more than 0.03 volt. Difference ______________ <0.03 volt Keysight 8478B Thermistor Mount...

  • Page 37: Troubleshooting

    3 and 4. The resistance should measure between 1000 and 5000 ohms. An open or shorted reading indicates the need for replacement of the thermistors. Under no conditions should the mount be required to carry a current higher than 14mA. Keysight 8478B Thermistor Mount...

  • Page 38: Thermistor Compensation

    3. Plug connector J2 into Model 432A. 4. Connect mount to 50Ω load. 5. Set: MOUNT RES: 200Ω POWER: If meter is pegged downscale: 1. Set RANGE to COARSE ZERO. 2. Set COARSE ZERO and adjustment to mid range. Keysight 8478B Thermistor Mount...
  • Page 39 37. If either screw bottoms, do not apply force. Thermistor replacement is indicated. When meter pointer rises, trim to zero with each adjusting screw. 5. Replace terminal shield and three screws (A). The instrument is now operative. Keysight 8478B Thermistor Mount...
  • Page 40 Maintenance Thermistor Compensation Figure 4-5 Thermistor Mount Assembly Keysight 8478B Thermistor Mount...
  • Page 41 5. Replace cover and three screws (A). The instrument is now operative. The three cover screws must be tight (use lock washers) for proper operation with 432A. If these screws are not tight noisy operation will occur. Keysight 8478B Thermistor Mount...

  • Page 42: Repair And Recalibration

    Repair and Recalibration If repair or recalibration of the mount is desired, the instrument may be returned to Keysight for repair and recalibration, or for recalibration only. Arrangements can be made with any Keysight Sales and Service office. Keysight 8478B Thermistor Mount...

  • Page 43: A.manual Changes

    “Unbalanced Operation with 431A/B or 430 Power Meters" and its first paragraph with following: If the 8478B is used with a Model 431 Power Meter, a Model 11527 A Adapter is required. If the 8478B is used with a 430 Power Meter, a Model 11528A Adapter is required.
  • Page 44 “8478B with Model 43IA/B and 430 Power Meters”. And add the following to the next paragraph, “The Model 11527A or 11528A Adapter is required when operating the 8478B with 43IA/B or 430 Power Meters respectively.” 5. Replace Figure 3-1...
  • Page 45 Manual Changes CHANGE A Figure A-2 84788 Connected to a 431 C Power Meter (P /0 Change A) 6. Replace Figure 4-4 on page 38 Figure A-3. Figure A-3 Printed Circuit Board (P/0 CHANGE A) Keysight 8478B Operation and Service Manual...

  • Page 46: Change B

    Figure 3-1 Figure 3-2 with Figure A-4 Figure A-5 respectively. Figure A-4 84788 Connected to a 432A Power Meter (P/0 Change B) Figure A-5 84788 Connected to a 431 C Power Meter (P/0 Change B) Keysight 8478B Operation and Service Manual...

  • Page 47: Change C

    38, Return C6 as it is shown in the manual (it was deleted by “CHANGE C”). CHANGE C 1. Replace Figure 3-1 Figure 3-2 with Figure A-6 Figure A-7 respectively. Figure A-6 8478B Connected to a 432A Power Meter (P /0 Change C) Keysight 8478B Operation and Service Manual...
  • Page 48 Manual Changes CHANGE C Figure A-7 84788 Connected to a 431 C Power Meter (P /0 Change C) 2. Replace Figure 4-4 on page 38 Figure A-8. Figure A-8 Printed Circuit Board (P/0 Change C) Keysight 8478B Operation and Service Manual...
  • Page 49 This information is subject to change without notice. © Keysight Technologies 1981-2018 Edition 3, March 2018 *08478-90015* 08478-90015 www.keysight.com...

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