HP 5334B Service Manual page 186

THE OSCILLATOR'S INTERNAL OVEN MASS TEMPERATURE MAY BE
AS HIGH AS 85°C (185°F). TO AVOID SERIOUS BURNS, DO NOT
REMOVE OSCIUTOR CIRCUITS AND/OR OVEN MASS ASSEMBLY
FROM THE OUTER HOUSING UNTIL THE OSCILLATOR HAS SUFFI-
CIENTLY COOLED (APPROXIMATELY
1
HOUR WITH BOTTOM COVER
AND FOAM INSULATOR REMOVED). THE OUTER HOUSING
TEMPERATURE IS NOT A RELIABLE INDICATION OF THE INTERNAL
TEMPERATURE.
d. Once the oscillator is cool enough to handle, remove the osdator assembly by pushing on the tuning
capacitor (FREQ. ADJ.) with a long, small diameter tool until the oscillator assembly can be
removed easily.
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.
e. Required Equipment:
Oscilloscope
.............................................
HP 1715A (or equivalent)
Power Supply
...........................................
12V dc
Preset power supply to
12V
dc. Turn off power supply before proceeding to the next step.
f. Connect the power supply to pins 2 (-) and 3 (+) of the 1 5 pin test connector, as shown in
Figure 8 - 1 1 . (See instructions in paragraph 8-386, Special Test Connector, to fabricate the test
connector.)
1 .
Insert the oscillator edge connector into the 15 pin test connector.
2. Connect pin 1 and 2 of the 1 5 pin test connector to an oscilloscope using a 5 0 f l coax cable. Set
the oscilloscope to 5 0 0 input. Do not apply power to the oven circuits.
g. Turn
on the power supply and adjust
R6 AGC
control for 1 . 5 6 V p-p
?
0.14V p-p.
h. Turn off the power supply and reassemble the oscillator if the problem is corrected.
8-430. EXCESSIVE DRIFT OF OUTPUT FREQUENCY. When the quartz crystal oscillator has not been
operated for a long period of time, or if it has been subjected to severe thermal or mechanical shock, the oscil-
lator may take some time to s t a b i i . In most cases, the crystal will drift and then stabilize at or below the
specified rate within a few days after being turned on. In isolated cases, depending on the amount of time the os-
cillator has been off and the environmental conditions it has experienced, the oscillator may take up to
1
week to
reach the specified aging rate. This should be taken into consideration if the drift rate of the unit is out of
HP
5334B -
Service Manual
8-66