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Al4 Frequency Control Assembly
Note
The block diagrams for the Al4 and Al5 assemblies are located in Chapter 11,
“Synthesizer Section.”
LODA
Drive
Refer to function block Z on the Al4 Frequency Control Schematic Diagram (sheet 3 of 5) in
the HP 8560 E-Series Spectrum Analyzer Component Level Information.
1. Set the HP 85623 to the following settings:
Center frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
..2MHz
2. On the HP 85623, press
C-1
and measure the signal power at the output of A7
(see item (1) of Figure 12-3).
3. If the output power is low, the output voltage of A14U429B at A14J18 pin 14 (item (2) of
Figure 12-3) 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 A14J18 pins 5 and 13, item
(4),
are consistent with the operational amplifier output.
Note
If a TAM is available, use Manual Probe Troubleshooting to make
measurements on A14J18 pins 5, 13, and 14. These voltages are referred to as
AMP CNTL, LO SENSE, and PIN
ATTEN
respectively.
4. If the voltages measure as indicated in step 3, measure the All YTO output. (See item (3)
of Figure 12-3.)
5. If all measurements are within limits, refer to “A7 LO Distribution Amplifier” in this
chapter.
RF Section 12-l 1