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RCA CrY8tal.Calibrated Marker Generator WR·99A
lOMe:
STAHMRD
OSCILLATOR
1
@-+-I
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11
Fiture 15. Test setup for alignment of 10-Mc oscillator.
WR-99A
IIo4AAKCA
ADDEA
Ar
OUT
Q
CAO
IWe
STANDAAD
0
OSCILLATOA
Ar
OUT
0-
,__
VCA"!:
Figure 16. Tesl setup for alignment
of l-Mc oscillator.
4. Set the RF control to "ON" and carefully check
between the 30. and 4O·Mc points for a strong beat at
each I·Mc dial mark. If the check points are at other
than I·Mc intervals,
adjust LlO to the next lock-in
point, higher or lower as required, to give the required
sub-multiple of 10 Me.
5. Adjust the core of LI0 and observe the adjust.
ment range over which correct look-in occurs: Reset
the core to the center of the lock-in range.
4.5-Mc Oscillator Adjustment
Alignment of the 4.5·Mc oscillator requires, in ad-
dition to the WR:99A, a cathode-ray oscilloscope, such
as the RCA WO-91A, a I·Mc standard oscillator, such
as
the Measurements
model Ill, and a marker-adder
unit, such as the RCA WR-70A RF /IF/VF
Marker
Adder.
1. Connect the equipment as shown in the test setup
of figure 16.
2. With power applied to all units, set the CAL/
MOD control on the WR-99A to "4.5 MC MOD". Set
all attenuator
switches to "OUT" and set.the RF con-
trol to "OFF"
3. Adjust
the amplitude
controls
on the market-
adder unit to observe the beat on the oscilloscope
screen between the second harmonic
(9 MC) of the
4.5-Mc oscillator in the WR-99A and the ninth har-
monic from the I-Mc standard
oscillator.
WA-99A
SWEEP
(;'[NEAATOA
STANDAAD
SIGNAL.
(;.[NEAATOA
Ar
Ar
Ar
OUT
OUT
9
OUT
(
T
CRO
WAAKEA
0
ADDEA
'--
~9
VCAT.
I
Figure 17. r.st
selup for vfo tracking adiustments.
4. Adjust trimmer capacitor
C41 to obtain as close
zero beat as possible.
VFO Tracking Adjustments
NOTE: All vio adjustments
must be made in the
order listed.
Band 7 Adjustments.
Alignment
of the variable-
frequency
oscillator requires, in addition to the WR-
99A, a sweep generator,
such as the RCA WR·69A or
a WR-59-series unit, a marker-adder,
such as the RCA
WR-70A
RF /IF
/VF
Marker-Adder,
an oscilloscope
such as the RCA WO-9IA,
and a standard
signal
generator which can deliver output in the vhf region,
such as a Measurements model 80.
1. Connect the instruments as shown in the test setup
of Figure 17.
2. Set the RF RANGE control to band 7 (170 to
220 Me).
3. Adj ust the sweep generator
to deliver output on
channel 8. Set the standard
signal generator
and the
WR·99A to deliver output at 170 Me. Adjust the con-
trols on the marker-adder
and the oscilloscope to ob-
tain two markers on the oscilloscope sweep trace.
4. Adjust the high-frequency
trimmer,
C2, in the
WR-99A to approximately
the center of its range. Ad-
just inductor
L 7
until the two markers coincide on the
trace.
5. Tune the WR·99A and the standard
signal gen-
erator to 220 Me. Set the sweep generator
to deliver
output on channel lit.
6. Readjust C2 in the WR-99A to again coincide the
markers on the scope trace.
7. Repeat steps 4, 5, and 6, as necessary, until both
ends of the band-7 frequencies track correctly.
8. Decrease the output from the standard signal gen-
erator and the sweep generator.
Set the CAL/MOD
control to "10 MC CAL". Recheck tracking at the 10·
Me points on band 7 and readjust, if necessary .
. 22 .
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