HP 8560A, Service Manual

Page: 407 / 450

Al4 Frequency Control Assembly
Note The block diagrams for the Al4 and Al5 assemblies are located in Chapter 10,
Synthesizer Section.
A7 LODA Drive
See function block Z of Al4 Frequency Control Schematic Diagram (sheet 3 of 5) in the
Component-Level Information binder.
1. Set the HP 8560A to the following settings:
CENTER FREQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MHz
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2 MHz
TRIGGER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..SINGLE
2. Measure the signal power at the output of A7 (see item (1) of Figure 11-2).
3. If the output power is low, output voltage, item pin 14) should
be above 0 V. If the output power is high, the voltage should be more negative than
-10 V. If the voltages do not measure as indicated, check that the voltages at pins
5 and 13, item are consistent with the operational amplifier’s output.
Note If a TAM is available, use Manual Probe Troubleshooting to make
measurements on
pins 5, 13, and 14. These voltages are referred to as
. AMP CNTL, LO SENSE, and PIN respectively.
4. If the voltages measure as indicated in step 3, measure the All YTO output. (See item (3)
of Figure 11-2.)
5. If all measurements are within limits, refer to “A7 LODA (LO Distribution Amplifier)” in
this chapter.
RF Section 1