TM 9-4935-294-15/2
5
If zero beat is till too mall, in-
Amplitude of zero-beat pattern in-
Defective double stub tuner.
Replace stub tuner.
sert double stub tuner between
creases
fundamental input of fre-
quency multiplier and isolator.
Adjust stubs for maximum
amplitude of zero beat.
6
Phase lock signal source.
Signal source phase locks as indi-
Defect within tunable synchronizer.
Refer to unable synchronizer
cated on tunable synchronizer.
manual.
7
Adjust REFERENCE OSCI-
Zero-beat pattern is displayed on
Defect within tunable synchronizer.
Refer to tunable synchronizer
LATOR FINE TUNE control
oscilloscope.
manual
to re-establish zero-beat pat-
tern on oscilloscope.
8
Determine input signal level by
Zero-beat display on oscilloscope.
Frequency converter overdriven or
Adjust attenuation of level-set at-
using signal input level to fre-
input from unit under test too
tenuator.
quency converter chart in
low.
chapter 2, section II, of TM
Defect within frequency converter.
Adjust output of unit under test.
9-4931-15/1 and adjust level-
Defect within oscilloscope.
Refer to frequency converter
*ct attenuator accordingly.
manual.
Connect VID OUT connector
Poor or improper connection in
Refer to oscilloscope manual.
on frequency converter to CH
test setup.
Locate poor or defective connec-
2 input connector on oscillo-
tion and correct.
scope. Adjust oscilloscope for
best display of channel 2
input. Tune frequency con-
verter in direction of decreas-
ing frequency until the first
zero beat is observed.
9
Adjust MIXER TUNE stubs
Zero-beat amplitude increases.
Defect within frequency converter.
Refer to frequency converter
for maximum amplitude of
Defect within oscilloscope.
manual.
zero beat.
Refer to oscilloscope manual.
10
Adjust level-set attenuator as re-
Zero-beat amplitude increase
Defect within frequency converter.
Refer to frequency converter
quired to obtain sufficient am-
manual.
plitude of zero beat.
11
Adjust main and FINE TUNING
Zero beat remains steady.
Defect within frequency converter.
Refer to frequency converter
controls on frequency con-
manual.
verter for precise zero beat as
Unit under test unstable.
Troubleshoot unit under test
indicated on oscilloscope.
12
Note digital counter readout at
Frequency display on digital
Defect within digital counter.
Refer to digital counter manual.
zero beat and record five most
counter.
significant figures, f H.
13
Tune frequency converter to next
Zero beat on oscilloscope and fre-
Defect within digital counter.
Refer to digital counter manual.
lower zero beat and record five
quency display on digital
most significant figures, fL.
counter.
14
Divide fH by fH - fL to obtain
Digital counter indicates fre-
Defect within digital counter.
Refer to digital counter manual.
harmonic number of fL. Set
quency of unit under test
Frequency converter set to incor-
Repeat 8 through 14.
3-5
