Table 3-1 Operational Check and Troubleshooting Chart of Frequency Measurement Setups for An Active Source Below 15 GHz
Step
Procedure
Normal indication
Possible cause of malfunction
Corrective measure
1
If approximate frequency of
Frequency converter overdriven or
source being measured is
input from unit under test too
uator.
known, determine signal level
low.
Adjust output of unit under te
using signal input level to
Defect within frequency converter.
Refer to frequency converter ma
frequency converter chart in
ual.
chapter 2, section II, of TM
Defect within oscilloscope.
Refer to oscilloscope manual.
9-4931-294-15/1 and adjust
Poor or improper connection in
Locate poor or defective conne
level-set attenuator accord-
test setup.
tion and correct.
ingly. If frequency of source is
slightly. Tune frequency con-
verter in direction of decreas-
ing frequency until the first
zero beat is observed.
2
Adjust MIXER TUNE stubs for
Zero-beat amplitude increases
Defect within frequency converter.
Refer to frequency converter ma
maximum amplitude of zero
ual.
beat.
Defect within oscilloscope.
Refer to oscilloscope manual.
3
Adjust level-set attenuator as re-
Zero-beat amplitude increases
Defect within frequency converter.
Refer to frequency converter ma
quired to obtain sufficient am-
ual.
plitude of zero beat.
4
Adjust main and FINE TUN-
Zero-beat remains steady.
Defect within frequency converter.
Refer to frequency converter ma
ING controls on frequency
.
nual
converter for precise zero beat
Unit under test unstable.
Troubleshoot unit under test.
5
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
.
6
Tune frequency converter to
Defect within digital counter
Refer to. digital counter manual
next lower zero beat and re-
quency display on digital
cord five most significant fig-
counter.
ures, fi,
7
Divide fH by fH-fL. to obtain
Digital counter indicates fre-
harmonic number of fL. Set
quency of unit under test.
.
HARMONIC PRESET selec-
of unknown signal source di-
rectly on counter display.
8
Tune frequency converter to fH.
Frequency display is the same as
Repeat 1 through 7.
Reduce setting of harmonic
obtained in 7 above.
too high.
selector switches by 1. Verify
the indication obtained in 7
3-3