Check A3 ADC MUX Function Block (steps 1-4)

1.Connect the positive lead of a DVM to A15J200 pin 13 and the negative lead to A15J200 pin 6. This measures the sampling oscillator tune voltage which is an input to the A3 interface assembly ADC MUX.

2.Set the spectrum analyzer to the following settings:

Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389.5 MHz Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Single

3.Use the data entry keys to tune the CENTER FREQ to the values listed in Table 11-4.

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.

Table 11-4. Center Frequency Tuning Values

HP 85623

sampling

Center Frequency (MHz)

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

Check A14J301 10 MHz reference 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lO MHz 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 10 MHz distribution on Al5 and A21 OCXO (If not Option 103).

8.Reconnect W37 to A14J301.

Synthesizer Section 1 l-9

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Agilent Technologies 856290216 Check A3 ADC MUX Function Block steps, Center Frequency Tuning Values, Synthesizer l-9