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A9 Input Attenuator
1. Perform the “Input Attenuator Switching Uncertainty” performance test in Chapter 2,
“Using Performance Tests,” of the HP 8560 E-Series Spectrum Analyzer Calibration Guide.
2. If there is a step-to-step error of approximately 10 dB or more, continue with step 3.
3. On the spectrum
highlighted.
analyzer,
press
(AMPLITUDE),
and
ATTEN
AUTO
MAN until
MAN
is
4. Step the input attenuator from 0 dB to 70 dB. A “click” should be heard at each step. The
absence of a click indicates faulty attenuator drive circuitry. It will be necessary to use
the DATA keys to enter an input attenuator setting of 0 dB (the step key will not allow
selecting 0 dB input attenuation).
5. Monitor the pins of A14U420 with a logic probe or DVM while setting the input attenuator
to the values listed in Table 12-3.
6. If one or more logic levels listed in the tables is incorrect, disconnect
Wll
from A14J6 and
repeat step 4 checking only pins 3, 5, 11, and 13 of A14U420. Pins 4, 6, 10, and 12 should
all read low TTL levels.
7. If one or more logic levels listed in the tables is incorrect with
Wll
disconnected,
troubleshoot the Al4 frequency control assembly.
8. If all logic levels are correct, the A9 input attenuator is probably defective.
12-8 RF Section