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7. Connect a 10 MHz, −2 dBm, signal to the rear panel 10 MHz REF
8. Check the signals at A15J301, A15J302, A15J303, and A15J304
9. If the signals are correct in EXTernal operation, but not in INTernal
10.If the signal at U304 pin 13 is correct (see
Figure 12-9
10 MHz Reference at A15J302
Chapter 12
IN/OUT connector.
according to the procedure in steps 2 through 4.
operation, the problem lies in A21 OCXO (or Option 103 TCXO), its
voltage reference, or the TTL level generator. Check these areas as
follows:
a. On the spectrum analyzer, press
b. Check U305 pin 3 for approximately +12 Vdc (Option 103 only).
c. Check, with an oscilloscope, for a 10 MHz sine wave greater than
or equal to 1 V p-p at J305, or at U302 pin 3 (with Option 103).
628), but there is a problem with the signals at A15J301, A15J302,
A15J303, or A15J304, suspect U303 or U304 in the 10 MHz
Distribution circuitry.
A15 RF Assembly
.
10 MHz INT
Figure 12-10 on page
RF Section
627
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