A9 Input Attenuator - HP 8560E Service Manual

RF Section

A9 Input Attenuator

A9 Input Attenuator
1. Perform the "Input Attenuator Accuracy" test in the HP 8560
2. If there is a step-to-step error of approximately 10 dB or more,
3. On the HP 8560E/EC, press
4. Step the input attenuator from 0 dB to 70 dB. A "click" should be
5. Monitor the pins of A14U420 with a logic probe or DVM while
The logic levels listed in
NOTE
usage (Pin 5 low, Pin 6 high). DC usage (Pin 5 high, Pin 6 low) is not
shown.
6. If one or more logic levels listed in
7. If one or more logic levels listed in
8. If all logic levels are correct, the A9 input attenuator is probably
592
E-Series Spectrum Analyzer Calibration Guide.
continue with step 3.
is underlined.
MAN
heard at each step. The absence of a click indicates faulty attenuator
drive circuitry.
setting the input attenuator to the values listed in
page 593.
incorrect, disconnect W11 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.
incorrect with W11 disconnected, troubleshoot the A14 frequency
control assembly.
defective.
, and
AMPLITUDE
Table 11-3 on page 593
Table 11-3 on page 593
Table 11-3 on page 593
until
ATTEN AUTO MAN
Table 11-3 on
show the default AC
is
is
Chapter 11