OPTION
-130
HIGH STABILITY REFERENCE
The Ovcncd Oscillator
output is disabled
when
the
control line
EXREFL is set
low,
i.e.,
when the REF INT
/
EXT
switch is
set
to
EXT during external reference
operation.
The
status line HSOPTL, normally at +5V, is pulled to ground when the High-Stability
Reference option Is
installed.
130»4. ADJUSTMENTS
TEST EQUIPMENT
Frequency Standard
Oscilloscope
Two 3-ft. 50-Ohm coaxial cables, Y9II1
REMARKS
The voltage adjustment (A3A2Al’R4) should be made after
the first half hour of the
three-hour
Generator warmup period has begun. For the best results in the
frequency
accuracy adjustment, the
Generator should be
operated at
room
temperature for
at
least
three hours
before
continuing
with the
adjustment
procedures.
PROCEDURE
The
High-Stability Reference Power supply voltage is first adjusted. Then
the UUT
reference
and
the Frequency Standard waveforms are viewed on the
oscilloscope
while
triggering
on
the Frequency Standard. The evened oscillator FREQ ADJ, COARSE,
and then FINE are
adjusted for
a stationary display.
Voltage Adjustment
1.
Remove the Generator top cover.
2. Connect the
DMM
to
the
UUT.
Connect the positive lead to TPl and the
negative lead to TP3.
3. Adjust R4
for
23.4
±
0.1 V.
4. Remove the DMM connections from the UUT and
replace
the top cover
(temporarily). Wait the remaining Generator warmup time, and perform
the
frequency
accuracy
adjustment.
Frequency Adjustment
1.
Remove the top Generator cover and the two FREQ ADJ access .screws from
the top of
the evened oscillator.
2. Connect the Frequency
Standard
signal to the oscilloscope vertical input
channel 1,50 Ohms termination. Connect the UUT rear panel 10
MHz
OUT
to
the
oscilloscope vertical input channel
2,
50 Ohms termination.
3.
Set the
UUT
rear
panel UUT
REF INT/EXT switch to INT,
4. Set the vertical controls of the oscilloscope to display the UUT
lO-MHz
signal
and
the Frequency Standard 10-MHz
signal. Set
for internal triggering on
channel
1,
and adjust timebase for O.l/xsec/div.
130-2
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