Chapter 11 529
Synthesizer Section
Confirming a Faulty Synthesizer Section
4. As the sampling oscillator frequency is increased, the DVM reading
should also increase. If the tune voltage is correct, but the ADC
measures the voltage and determines it to be out of specification,
troubleshoot the A3 assembly ADC MUX.
Check A14J301
10 MHzreference
input (steps 5-8)
5. Disconnect W37 from A14J301.
6. Connect a test cable from W37 to the input of another spectrum
analyzer. Tune the other spectrum analyzer to the following settings:
Center frequency .................................................... 10MHz
Span .......................................................................... 2MHz
7. The amplitude of the 10 MHz reference signal should measure
>−1 dBm. If the signal does not measure >−1 dBm, troubleshoot the
A15 10 MHz distribution and A21 OCXO (If not Option 103).
8. Reconnect W37 to A14J301.
Check 1st LO
(steps 9-11)
9. Connect the CAL OUTPUT to INPUT 50Ω.
Table 11-2 Center Frequency Tuning Values
8564ECand8565ECCenter
Frequency (MHz)
Sampling Oscillator Frequency
(MHz)
2156.3 285.000
2176.3 286.364
2199.5 287.500
2230.3 288.462
799.3 288.889
2263.3 290.000
2282.3 290.909
2302.3 291.667
2155.3 292.500
2158.3 293.478
2336.3 294.444
2196.3 295.000
1.3 296.000
2378.3 296.471
2410.3 297.000
2422.3 297.222
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