Turn On And Warmup; Frequency Reference; Internal Oven Reference - HP 3585A Service Manual

Model 3585A
3·2. TURN ON AND WARMUP
Before applying ac line power to the 3585A, make certain that the rear-panel VOLTAGE
SELECTOR switch is in the position that corresponds to the voltage and frequency of the ac
power source. Also verify that the proper line fuse is installed in the rear-panel fuse holder
(see Section II) .
The 3585A specifications are met after a 20-minute warmup at the ambient operating
temperature.
3·3. Frequency Reference
The 3585A can be operated using its own internal Oven Reference or an external frequency
reference. The internal or external frequency reference must be connected to the rear-panel
EXT REF IN connector.
3·4. Internal Oven Reference
The 3585A is equipped with a temperature-stabilized, crystal-controlled 10 MHz reference
oscillator, whose output is available at the rear-panel OVEN REF OUT connector. The fre­
quency accuracy of this internal Oven Reference is expressed as a time coefficient of 10 MHz
± 1 x 1 0-7 per month, relative to the time the instrument is shipped from the factory or the
reference frequency is adjusted using the procedure outlined in Volume One of the Service
Manual. The Oven Reference time coefficient is included in the Counter and Manual fre­
quency accuracy specifications.
To use the internal Oven Reference, connect the BNC to BNC j umper (supplied with the in­
strument) between the rear-panel OVEN REF OUT and EXTERNAL REF IN connectors.
1. Power is applied to the internal reference oven only when the
LINE switch is in the ON position. The 3585A does not have a
"standby " mode.
2.
The output of the internal Oven Reference is
oven reaches the proper operating temperature. During the oven
warmup cycle, there is no signal applied to the EXT REF IN con­
nector; so the 3585A 's master oscillator runs in the open-loop
mode in which the frequency accuracy is unspecified. When the
oven reaches the proper operating temperature (about ten minutes
after turn on), the Oven Reference is automatically enabled. At
that time, the beeper sounds and the message,
UNLOCKED " momentarily appears on the CR T screen. The
message disappears as soon as the master oscillator is phase-locked
to the Oven Reference.
NOTES
disabled
Operation Overview
until the
"L. O.
3-3