HP 8753E - Rechecking the A13;A14 Fractional-N

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Figure 7-24. High Quality Comb lboth at 3 GHz
3. If the signaI at the A7 output is good, check the A7-to-A4 cable.
4. If the signal is not as clean as F’igure 7-24, observe the HI OUT input signal to
the A7 assembly.
. . . . . . . . . :<.+“:.::’ .;..,./. ,............... . . . . . . . . . . .
./,, ../ ..:.. .,. . . . . . . .
a. On the network analyzer, press [~Systeml~~~~~~~‘.~:~:~~ #@F%$l$, !@&&
...?? ::.:.::,.,:.:....:.:.:,~:;:;::::~:::~~~~~~..~ >E .;y: ( .,
~~~~~~~~~~. &he&e do not readjust the instrument. Remove the
::: ... . . . . . z.2 :.... z :...... 2: . . . . ~.;..:....~.i
.,:si . . . . . i.;,.~......_~......i
A14-to-A7 SMB cable (WQ) from the A7 pulse generator assembly
(CW B 16 MHz).
b. Set the spectrum analyzer to a center frequency of 45 MHz and a span
of 30 MHz. Connect it to the
A14-to-A7 cable still attached to the Al4
assembly. Narrow the span and bandwidth to observe the signal closely.
5. If the HI OUT signal is as clean as Figure 7-25, the
A7 assembly is faulty.
Otherwise, check the A14-to-A7 cable or recheck the A13/A14 fractional-N as
described ahead.
Rechecking the A13/A14 Fractional-N
Some phase lock problems may result from phase noise problems in the
fractional-N loop. lb troubleshoot this unusual failure mode, do the following:
1. Set the network analyzer at 60 MHz in the FRACN TUNE mode.
Source Troubleshooting 7-33