HP 3585A Service Manual page 121

Model 3585A
5·8. Oven Output Shutdown Adjustment
This adjustment sets the point where the Oven Oscillator will begin to be used as the 3585A's
reference. During warm-up the Oven Oscillator's frequency is locked to the
oscillator. This adjustment causes the OVEN REF OUT to be shut-off during this warm-up
period.
With the 0 V EN power cable disconnected, allow the instrument to
warm up 20 minutes or more be fore beginning this ad justment.
a. Connect OVEN Power Cable. (A8I J2)
b. Remove the jumper between the OVEN REF OUT and the EXT REF IN on the
3585A.
c. Connect the OVEN REF OUT to the 3585A 50n input.
d. After the 3585A has completed Autoranging, turn the AUTO RANGE function off.
e. Adjust A81 R9 (SHUT) to the point where the lOMHz signal level just turns off
(on + 7 dBm
....
f. Adjust A8 1 R9 one eighth turn counter-clockwise.
g. Replace the jumper between the OVEN REF OUT and the EXT REF IN.
h. Disconnect all inputs to the counter and the 3585A. Connect the 3585A l OMHz. Ref
Output to the 3335 40/N Ref Input.
i. This completes the Reference Oscillator Adjustments.
5·9. 1 DMHz Oven Oscillator Adjustments
This adjustment sets the frequency of the 3585A oven oscillator. It is important that a fre­
quency counter with greater accuracy and stability than that of the 3585A reference be used
for this adjustment.
All instruments used for this ad justment should be turned on for
at least 20 minutes (pre ferably longer) prior to beginning ad­
justments.
a. Remove any connections between the synthesizer reference connectors and the 3585A
rear panel reference connectors.
b. Connect both the 3585A and the synthesizer
3585A, use the supplied BNC shorting bar to connect the OVEN REF OUT to the EXT REF
IN.
NOTE
off .... -35dBm).
NOTE
to
their own internal references. For the
Adjustments
90
MHz ref.
5-7