Chapter 12 603
RF Section
A7 LO Multiplier and Distribution Amplifier
9. The measured voltage should be approximately +5 Vdc. If the
voltage is not +5 Vdc, troubleshoot the A14 frequency control
assembly.
10.Connect the positive lead of a DVM to A14J18 pin 15. The voltage
should measure within ±10 mV of the Gate Bias voltage listed on the
A7 label.
11.If this voltage is not within the correct range, refer to the "LO
Distribution Amplifier Adjustment" in Chapter 2, adjustment
procedures.
12.If the voltage varies between 0 Vdc and −2 Vdc, adjust the Gate Bias
for a DVM reading within ±10 mV of the Gate Bias voltage listed on
the A7 label. If the voltage does not vary between 0 Vdc and −2 Vdc,
troubleshoot the A14 Frequency Control Assembly.
13.Disconnect the jumper from A14J19 to A14J10. Press
LINE to turn
the spectrum analyzer off. Reconnect W12 to A14J10. Press
LINE to
turn the spectrum analyzer on.
14.If the DVM reading changes significantly, the A7 is probably
defective.
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