Output Amplitude Adjustment; Figure 5-2. 10811A Amplitude Adjustment Set-Up - HP 10811A Operating & Service Manual

5-14. OUTPUT AMPLITUDE ADJUSTMENT

5-15. The output amplitude is adjusted by the setting of the variable resistor R6 which is in the
feedback of the AGC circuitry. It is not accessible from the outside of the oscillator.
5-16. The following procedure should be used to adjust the output amplitude only if the output level falls
outside the specified level, or repairs have been made to the main oscillator or AGC circuitry.
1. Remove oscillator from instrument.
THE OSCILLATOR'S INTERNAL OVEN MASS TEMPERATURE MAY
BE AS HIGH AS 85°C (185°F). TO AVOID SERIOUS BURNS DO NOT
REMOVE OSCILLATOR CIRCUITS AND/OR OVEN MASS ASSEMBLY
FROM THE OUTER HOUSING UNTIL THE OSCILLATOR HAS
SUFFICIENTLY COOLED (APPROXIMATELY 1 HOUR WITH BOTTOM
COVER AND FOAM INSULATOR REMOVED). THE OUTER HOUSING
TEMPERATURE IS NOT A RELIABLE INDICATION OF THE INTERNAL
TEMPERATURE.
2. Remove bottom cover and allow oscillator to cool (if previously operated). To remove cover:
a. For the 10811A, remove the three screws securing the bottom cover. Remove the two screws
securing the P.c. edge connector to the outer can. Remove the top foam insulator to expose
the oscillator circuits.
CAUTION
DO NOT pull the oscillator out of the outer
housing by pulling on the P.C. edge
connector or flex circuit!!
b. For the 10811B remove the four
screws securing the bottom
cover. Disconnect the bottom
cover flex circuit from the seven
pin connector.
3. Once the oscillator is cool enough to
handle, remove the oscillator assembly by
pushing on the tuning capacitor (top of
oscillator) with a long, small diameter tool
until the oscillator assembly can be
removed freely.
NOTE
Under no circumstances should the oven
circuit be operated with the oven mass
removed from the outer housing. To do so
will cause damage to components inside the
oven mass.
4. Obtain HP Model 6215A Power Supply or
equivalent. Preset power supply to 12V dc.
Turn off power supply before proceeding
to next step.
WARNING

Figure 5-2. 10811A Amplitude Adjustment Set-up

Model 10811A/B
27