Chapter 12
623
RF Section
A15 RF Assembly
CAUTION
For troubleshooting, it is recommended that you use an active probe,
such as an 85024A, and a second spectrum analyzer. If an 1120A active
probe is being used with a spectrum analyzer having dc coupled inputs,
such as the 8566A/B, 8569A/B and the 8562A/B, either set the active
probe for an ac-coupled output or use a dc-blocking capacitor between
the active probe and the spectrum analyzer input. Failure to do this can
result in damage to the spectrum analyzer or the probe.
4. Use an active probe with a second spectrum analyzer to measure the
signal at A15TP601 (function block C). The signal should measure
−
17 dBm
±
4 dB confirming the operation of the 2nd IF Amplifier.
5. Use an active probe with a second spectrum analyzer to measure the
300 MHz into the LO port of the third mixer. The signal should
measure at least +20 dBm.
6. Measure the 10.7 MHz IF output power of the mixer. The signal level
should be approximately
−
22 dBm.
7. Move the WR PROT/WR ENA jumper on the A2 controller assembly
to the WR ENA position.
8. While measuring the signal at the mixer 10.7 MHz IF output, adjust
the signal source until the level of the 10.7 MHz IF is
−
40 dBm.
9. On the spectrum analyzer, press
SGL SWP
,
CAL
,
IF ADJ
OFF
,
MORE 1 OF 2
, and
FLATNESS
. Increase the gain of the flatness
compensation amplifiers to maximum by entering 0 using the data
keys. This sets the gains in the flatness compensation amplifiers to
their maximum values.
10.Connect the second spectrum analyzer to A15J601 and measure the
10.7 MHz IF signal level. The signal should measure greater than
−
10 dBm. If the signal level is incorrect, continue with step 13.
11.Enter 4095 into the spectrum analyzer flatness data. The signal
level at A15J601 should measure less than
−
36 dBm. This sets the
gain of flatness compensation amplifiers to a minimum. If the signal
level is incorrect, continue with step 13.
12.Check that the gain stages are properly biased and functioning.
13.Check the attenuator stages and flatness compensation control
circuitry.
a. For minimum gain (flatness data equals 4095), RF GAIN
(A15U909 pin 10) should be at
−
1.6 Vdc and the current through
each section as measured across R667 or R668 should be about
7 mA.
Summary of Contents for 8564EC
Page 17: ...25 1 General Information ...
Page 37: ...47 2 Adjustment Diagnostic Software ...
Page 77: ...89 3 Manual Adjustment Procedures ...
Page 129: ...161 3a Manual Adjustment Procedures 3335A Source not Available ...
Page 142: ...175 4 Assembly Replacement ...
Page 194: ...Chapter 4 257 Assembly Replacement Procedure 13 A21 OCXO Figure 4 34 A21 OCXO Mounting Screws ...
Page 196: ...259 5 Replaceable Parts ...
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Page 224: ...303 6 Major Assembly and Cable Locations ...
Page 234: ...315 7 General Troubleshooting ...
Page 238: ...Chapter 7 319 General Troubleshooting Introduction Figure 7 2 Ribbon Cable Connections 1 of 3 ...
Page 239: ...320 Chapter7 General Troubleshooting Introduction Figure 7 3 Ribbon Cable Connections 2 of 3 ...
Page 242: ...Chapter 7 323 General Troubleshooting Introduction Figure 7 5 Service Cal Data Menu ...
Page 271: ...352 Chapter7 General Troubleshooting Block Diagram Description Figure 7 6 Functional Sections ...
Page 283: ...364 Chapter7 General Troubleshooting Block Diagram Description ...
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Page 287: ...377 8 ADC Interface Section ...
Page 291: ...Chapter 8 381 ADC Interface Section Introduction Figure 8 2 A3 Test Connector Pin Locations ...
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Page 322: ...427 9 IF Section ...
Page 356: ...Chapter 9 461 IF Section A5 IF Assembly Figure 9 13 Detailed IF Adjust Signature 5 ...
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Page 379: ...487 10 Controller Section ...
Page 394: ...521 11 Synthesizer Section ...
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Page 454: ...593 12 RF Section ...
Page 489: ...628 Chapter12 RF Section A15 RF Assembly Figure 12 10 10 MHz TTL Reference at U304 Pin 13 ...
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Page 492: ...633 13 Display Power Supply Section ...
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Page 505: ...671 14 Component Level Information Packets ...
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