Troubleshooting When One Or More Inputs Look Good; Check The 4 Khz Signal - HP 8753D Option 011 Service Manual

Troubleshooting When One or More Inputs Look Good

Since at least one input is good, all of the common receiver circuitry beyond the multiplexer is
functional. Only the status of the individual sampler/mixers and their individual signal paths
is undetermined.

Check the 4 kHz Signal

1. Connect a cable from the RF OUT to input R.
2. Press
PRESET ENU
5 5
3. Use an oscilloscope to check the 4 kHz output of the sampler/mixer in question at the 10
assembly. The input and output access pins are listed in Table 8-2. The signal should
resemble the waveform of Figure 8-6.
If the signal is good, continue with \Check the Trace with the Sampler Correction
Constants O ."
If the signal is bad, skip ahead to \Check 1st LO Signal at Sampler/Mixer."
nemonic
IFR
IFA
IFB
Figure IFW VE8 here.
8-8 Receiver Troubleshooting
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.
W FREQ
Table 8-2. 2nd IF (4 kHz) Signal Locations
Description
4 kHz
4 kHz
4 kHz
Figure 8-6. 2nd IF (4 kHz) Waveform
A10 Location
A10P1-1, 31
A10P1-4, 34
A10P1-7, 37
Signal Source
A4P1-6
A5P1-6
A6P1-6
RAFT
3/21/106 15:13