418 Chapter10
Analyzer Options and Block Diagrams
Tracking Generator 8593E, 8594E, 8595E, 8596E Option 010
If there is no output power
The A3A15 assembly requires power supplies, a 1st LO signal, and a
600 MHz drive signal in order to provide power output.
1. Check the power supplies on A10J1 and A3A15J1. Refer to the A10
Tracking Generator Control assembly schematic.
2. Verify that the voltage at A10J1 pin 4 is greater than +14 Vdc when
the tracking generator is on. If the voltage is not greater than
+14 Vdc, troubleshoot A10.
3. Check that ALC_EXT, measured at A10J1 pin 10, is at a TTL low
when the tracking generator is set to ALC INT and at a TTL high
when the tracking generator is set to ALC EXT.
4. Check that the 600 MHz drive signal is −8 dBm ±3.5 dB. If the signal
is outside of this range, troubleshoot the A9 Third Converter
assembly.
5. Check that the 1st LO input signal is +16 dBm ±2 dB. Perform the
LO OUTPUT amplitude check described in “If the output goes
unlevelled (TG UNLVL message displayed).” earlier in this section,
measuring instead at the end of W41 nearest A3A15.
6. Check the tracking adjustment controls. Monitor A10J1 pin 5 with a
DVM. On the 8594A, use the step keys and knob to change the MAN
TRACK ADJUST value from 0 to 4095. The voltage measured should
increase from 0 V to +12 V.
CAUTION The following step requires adjustment of A3A15C3. The lifetime of
A3A15C3 is rated for less than 10 cycles. Do not adjust A3A15C3 unless
it is absolutely necessary.
7. If all of the checks above are acceptable, the tracking oscillator
might not be functioning. Set up the 8594A as indicated in the
Tracking Oscillator adjustment procedure in Chapter 2, using an
analyzer, such as an 8566A/B, in place of the frequency counter. Try
to adjust A3A15C3 until a signal is displayed on the 8566A/B. If
adjusting A3A15C3 does not result in the tracking generator
beginning to function, the A3A15 Tracking Generator assembly is
suspect.
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