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HP 8970B Service Manual Download Page 18

3-2

HP 8970B Option 020 Service Manual Supplement

Adjustments
General

General

There are 2 adjustments that need to be made:

1. Input power detector gain and offset.

2. The 600 MHz SAW oscillator frequency adjustment.

Input power detector Gain and Offset Adjustment

Follow the adjustment procedure in section 5-13 of the Adjustments Chapter in the 8970B
Service Manual with the following exceptions.

Figure 3-1: Input detector gain and offset adjustment

1. The input level must be -21 dBm

±

0.1 dB.

2. R32 is the offset adjustment.

3. R26 is the gain adjustment.

R32

R26

J1

RF Input
Assembly

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Summary of Contents for 8970B

Page 1: ...HP 8970B Option 020 Service Manual Supplement ...

Page 2: ......

Page 3: ...Service Manual Supplement HP 8970B Option 020 HP Part no 08970 90115 Edition 1 May 1998 ...

Page 4: ...countries OSF Motif is a trademark of the Open Software Foundation Inc in the USA and other countries Copyright Hewlett Packard Company May 1998 All rights reserved Reproduction adaptation or translation without prior written permission is prohibited except as allowed under the copyright laws Printed in the UK ...

Page 5: ...HP 8970B Option 020 Service Manual Supplement iii Printing History Printing History Date Manual Edition Notes May 1998 1 08970 90115 ...

Page 6: ...ations About this Manual This document is a supplement to the HP 8970B Noise Figure Meter Service Manual 08970 90054 and provides information useful for operating the HP 8970B Option 020 It also gives some troubleshooting tips HP Part Number Title 08970 90054 HP 8970B Noise Figure Meter Service Manual ...

Page 7: ...ment 3 2 600 MHz SAW Oscillator Frequency Adjustment 3 3 Board Differences 4 1 General 4 2 Microprocessor Board 4 2 20 MHz IF Assembly 08970 60050 4 3 Driver Assembly 08970 60089 4 4 Fault Finding Tips 5 1 General 5 2 Filter 0955 0634 5 2 Input Assembly 08970 60097 or 08970 60125 5 3 YIG Tuned Oscillator 0955 0630 5 4 Mixer 0955 0635 5 4 Isolator 0960 0638 5 5 4 5 GHz Low Pass Filter 9135 0169 5 5...

Page 8: ...Contents 2 HP 8970B Option 020 Service Manual Supplement ...

Page 9: ...1 Block Diagram and Parts List ...

Page 10: ...on 020 Front End Schematic 2 05 GHz Low Pass Filter 4 6 GHz Y T O J1 J3 J5 J2 J4 MIXER LO IF RF ISOLATOR I P O P 4 5 GHz LPF Second Convertor 600 MHz SAW Oscillator J5 J4 J3 J2 J1 INPUT ASSEMBLY PAD 1 PAD 2 PAD 3 924 TO A4 ASSEMBLY 925 926 20 dB AMP 923 15 V 2 DETECTOR 927 15 V 7 W1 W2 W3 W4 W5 W6 W7 W8 W9 92 0 92 2 50 Ω LO MONITOR ...

Page 11: ...d Schematic 10 dB 10 dB 10 dB 20 dB 2 7 GHz Isolator 4 5 GHz LPF 2nd Convertor X 6 600 MHz 3 6 GHz 300 MHz 10 2047 MHz 2050 MHz LPF INPUT ASSEMBLY 2 dB Detector Diode Output 3 910 5 947 GHz YTO Output To A4 Assy 3 9 GHz J3 J4 J5 J2 J1 Limiter Limiter on 08970 60125 Input Assembly only Suppresses externally generated transients ...

Page 12: ...e control lines On units using the Input Assembly 08970 60125 the Limiter suppresses externally generated transients In Figure 1 1 the numbers in brackets inside the input assembly refer to the wire colors The numbers at the side of the second convertor refer to the wire colors attached to the connector which connects up to the second convertor 10 dB PAD 20 dB AMP 10 dB PAD 10 dB PAD Detector 3 GH...

Page 13: ...mbly 08970 601251 1 2 to 8 GHz YIG Tuned Oscillator 0955 0630 1 YIG Tuned Oscillator Interface Board 08970 60045 1 YIG Tuned Oscillator Shield 08590 00047 1 Semi rigid cable W2 08970 20081 1 Semi rigid cable W3 08970 20083 1 Semi rigid cable W4 08970 20085 1 Microwave Mixer 0955 0635 1 Semi rigid cable W5 08970 20084 1 Microwave Isolator 0960 0638 1 Right Angle SMA F to SMA M Adapter W6 1250 1249 ...

Page 14: ...1 6 HP 8970B Option 020 Service Manual Supplement Block Diagram and Parts List Material List ...

Page 15: ...2 Theory of Operation ...

Page 16: ...that any rejected signals are absorbed in the isolator and do not interfere with the front end detector circuitry The second convertor mixes 3900 MHz down to 300 MHz There is a cavity tuned bandpass filter which is tuned for 3900 MHz This is set at the factory and should not be adjusted The LO input is 600 MHz but this is multiplied up to 3600 MHz by a X6 circuit The 3600 MHz can be monitored at t...

Page 17: ...3 Adjustments ...

Page 18: ...ator frequency adjustment Input power detector Gain and Offset Adjustment Follow the adjustment procedure in section 5 13 of the Adjustments Chapter in the 8970B Service Manual with the following exceptions Figure 3 1 Input detector gain and offset adjustment 1 The input level must be 21 dBm 0 1 dB 2 R32 is the offset adjustment 3 R26 is the gain adjustment R32 R26 J1 RF Input Assembly ...

Page 19: ...igure 3 2 600 MHz SAW Oscillator Frequency Adjustment 1 Disconnect the 600 MHz SAW Resonator from the second convertor 600 MHz input 2 On the 8568A Press PRESET CENTRE FREQUENCY 600 MHz SPAN 500 KHz 3 Connect the 600 MHz SAW Resonator to the 8568A RF Input 4 Adjust R6 until the signal on the screen is 600 MHz 50 KHz 8568A 600 MHZ SAW Oscillator RF In ...

Page 20: ...3 4 HP 8970B Option 020 Service Manual Supplement Adjustments 600 MHz SAW Oscillator Frequency Adjustment ...

Page 21: ...4 Board Differences ...

Page 22: ... are a number of board differences that need to be documented here Microprocessor Board The same part number 08970 60033 is used in both instruments However the firmware is different for the option 20 compared to the standard Table 4 1 Firmware Part Numbers Options ROM 1 ROM 2 STD 08970 80050 08970 80051 Option 20 08970 80070 08970 80071 ...

Page 23: ...es from 7 5 pF 0160 3029 to 4 7 pF 0160 3873 2 R8 changes from 110 Ω 0757 0402 to 162 Ω 0757 0405 Figure 4 1 Schematic differences in 08970 600501 1 Differences are highlighted with a shaded background 15V F1 C23 0 01 uF L11 22 uH C22 0 01 uF R8 162 Ω 15V F1 R6 1000 Ω C83 4 7 pF R10 51 1 Ω C26 56 pF L12 1 5 uH C24 0 01 uF R9 1780 Ω 15V F1 R7 1000 Ω 20 MHz BANDPASS FILTER 14 6 TO 15 3 Vdc 6 5 TO 6 ...

Page 24: ...change from 214 2 Ω 0699 1911 to 121 Ω 0699 3460 2 Q2 is deleted and a wire is place between U33 pin 14 and the base of Q3 Figure 4 2 Schematic differences in 08970 600891 1 Differences are highlighted with a shaded background R25 121 Ω C28 1 uF Q3 U33D 12 13 14 3 3 L C55 1000 pF VR2 13V R24 3060 Ω 3 R26 121 Ω 3 R27 121 Ω 3 R39 121 Ω 3 R40 121 Ω 3 R41 3 19 8 1ST LO DRIVE 1ST LO GND R57 100 Ω C58 6...

Page 25: ...5 Fault Finding Tips ...

Page 26: ...nalyzer It is much easier to do it this way because the signals can be seen on the spectrum analyzer display Filter 0955 0634 The specifications on this part are The best way to measure this part is to use a network analyzer An alternate way is to use a spectrum analyzer e g 8593E with a tracking generator or a separate sweeper Verify over the frequency ranges above that the insertion losses are c...

Page 27: ...e the procedure RF Attenuator Checks in the Service Sheet BD1 section of the standard 8970B manual The voltages will be approximately correct It is also possible to measure the pads switching with the input section removed Using a 30 MHz signal at 20 dBm measure at J2 using a spectrum analyzer 1 Select Special 63 0 and take a reference on the Spectrum Analyzer straight through 2 Select Special 63 ...

Page 28: ...nce Level 20 dBm 4 Scale 2 dB division Ensure that the signal level measured on the spectrum analyzer is between 14 and 18 5 dBm Note You can monitor the YTO from J4 which is the unused side of the splitter However if you use this alternative be aware that the levels will be approximately 3 dB lower than when monitoring at J3 Mixer 0955 0635 The labelling on the schematic in figure 1 may be a litt...

Page 29: ...his will be at 3900 MHz The difference between the 2 signal levels should be less than 7 dB Isolator 0960 0638 This device will improve the match looking back from the 4 GHz low pass filter The insertion loss will be between 1 dB and 1 2 dB depending on the temperature This can be measured with a network analyzer a spectrum analyzer and tracking generator or a spectrum analyzer and sweeper The ope...

Page 30: ...is the RF input at 3900 MHz 2 J2 is the IF output at 300 MHz 3 J3 is not used 4 J4 is the LO input at 600 MHz Power should be between 1 and 4 dBm 5 J5 is the LO monitor at 3600 MHz This is about 30 dBm with the above input range for the 600 MHz The conversion loss between the 3900 MHz input at J1 and the 300 MHz output at J2 is about 6 dB With a 25 dBm input signal at J1 the output at J2 would be ...

Page 31: ...6 Board Details ...

Page 32: ...6 2 HP 8970B Option 020 Service Manual Supplement Board Details Figure 6 1 600 MHz SAW Oscillator Component Layout Drawing ...

Page 33: ...HP 8970B Option 020 Service Manual Supplement 6 3 Board Details Figure 6 2 600 MHz Schematic ...

Page 34: ...6 4 HP 8970B Option 020 Service Manual Supplement Board Details Figure 6 3 Input Section Component Layout Drawing for Assembly 08970 60097 ...

Page 35: ...HP 8970B Option 020 Service Manual Supplement 6 5 Board Details Figure 6 4 Input Section Schematic for Assembly 08970 60097 ...

Page 36: ...6 6 HP 8970B Option 020 Service Manual Supplement Board Details Figure 6 5 Input Section Component Layout Drawing for Assembly 08970 60125 ...

Page 37: ...HP 8970B Option 020 Service Manual Supplement 6 7 Board Details Figure 6 6 Input Section Schematic for Assembly 08970 60125 ...

Page 38: ...6 8 HP 8970B Option 020 Service Manual Supplement Board Details Figure 6 7 HP 8970B Option 20 Hardware YTO W2 Input Section A6 W3 W4 Mixer Isolator W5 4 5 GHz LPF Second Convertor 600 MHz SAW Oscillator ...

Page 39: ......

Page 40: ...Reorder No 08970 90115 Copyright 1998 Hewlett Packard Ltd Printed in UK May 1998 Manufacturing Part No 08970 90115 ...

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