TM9-4935-294-15/2
Table 3-18. A-Band Rf Head Test Chart.
Test equipment control
Rf head control
Possible cause
Step
positions or operation
positions or operation Normal indication
of malfunction
Corrective measure
1
Set up signal source, utilizing
Set FREQUENCY-MC
Power meter indicates 0.5
R1505 out of adjustment
Adjust R1505 as indicated
A-band rf bead under test
control to 38, 250 MHz.
mw.
or defective.
in technical bulletin TB
for leveled operation as
9-4931-302-50,or re-
shown in figure illustrating
place, if defective.
setup for signal source
leveling in chapter 2, see-
Broken connector pin in
Replace broken pin.
tion II, of TM 9-4931-294-
P701 (rf head connec-
15/1. Operate signal source
tor)
in CW mode of operation,
but do not remove the
Defective resistor R1507,
Replace defective compo-
second directional coupler.
R1401, R1402 or choke
nent.
Connect thermistor mount-
L1401.
power meter combination to
the second directional coup-
Defective BWO tube.
Replace BWO tube as in-
ler and set RF LEVEL-
dicated in paragraph
LEVEL ADJ control for an
4-22.
indication of 0.6 mw on
power meter.
2
Same as 1 above.
Slowly adjust FRE-
The 0.5 mw indication on
R1605 out of adjustment
Adjust R1505 as indicated
QUENCY-MC control
power meter does not
or defective.
in TB 9-4931-302-50,
through its entire
vary by more than 2.5
or replace, if defective.
range.
db.
Defective BWO tube.
Replace BWO tube as in-
dicated in paragraph
4-23.
3
Disconnect thermistor mount
Adjust FREQUENCY-
Signal source phase-locks
Mixer diode CR101 defec-
Replace mixer diode
from directional coupler.
MC control in 1350
as indicated on tunable
tive.
CR101.
Connect frequency mesure-
MHz steps, beginning
synchronizer.
ment system(refer to
at 26,500 MHz, through
Directional coupler CP101
Replace directional cou-
figure illustrating setups for
its entire range.
defective.
pler CP101.
frequency measurement of
an active source above 12.4
Frequency measurement
Helix voltage shaper cir-
Adjust the circuits indi-
GHz in chapter 2, section
system indications cor-
cuit out of adjustment
cated as outlined in TB
III, of TM9-4931-294-
respond to within 2%
or defective.
9-4931-302-560 or, if de-
15/1) to the auxiliary arm
of the frequency indi-
fective, locate and re-
of the second directional
cated on the rf head
place defective compo-
coupler in the setup. Phase-
counter.
nent.
lock signal source at each
of the 11 frequency settings.
HV limit circuit (R1403,
R1404 and R1405) out
3-70