TM 11-6625-2398-15-3
Symptom
Probable trouble
Correction
1. Excessive RF sum
Improper connections
Check that connections to A1HY1J1, A1HY1J2
channel insertion loss
and the connections of A1W1 are secure. Tight-
en loose connections and replace defective con-
nectars.
Defective cable
Check difference channel insertion loss (para
A1W1 or hybrid
6-9). If the sum channel and difference channel
coupler A1HY1
insertion losses are both excessive, check cable
from A1J1 to A1HY1J1. If cable is not at fault,
replace hybrid coupler A1HY1 and recalibrate
insertion losses (para 6-8 and 6-9). If only the
sum channel has an excessive loss, replace cable
A1W1 and recalibrate (para 6-8).
2. Excessive RF differ-
Improper connections
Check that all connections to A1J5 and A1J1
ence channel inser-
are made, and are secure. Tighten loose con-
tion loss (para 6-9)
nections and replace defective connectors.
Defective cables,
Check sum channel insertion loss (para 6-8). If
attenuator, or hy-
sum channel and difference channel insertion
brid coupler A1HY1
losses are both excessive, check cable from
A1J1l to A1HY1J1. If cable is not at fault, re-
place hybrid coupler A1HY1 and recalibrate
insertion losses (para 6-8 and 6-9). If only the
difference channel has an excessive loss, check
cable A1W3, cable A1W2, attenuator A1AT1
and the cables from A1J4 and A1J5 to attenua-
tor A1AT1. Replace defective parts and recali-
brate (para 6-9 and 6-10).
3. Excessive VSWR
Improper connections
Check all connections between the input show-
(para 6-11)
ing excessive VSWR and the termination(s);
tighten loose connections, replace defective con-
nectors and recalibrate (para 6-8, 6-9 and 6-10).
Defective parts
Check cables A1W1, A1W2, attenuator A1AT1,
hybrid coupler A1HY1, cable A1W3 and the
cables from A1J1, A1J4 and A1J5. Replace de-
fective parts and recalibrate (para 6-8, 6-9 and
6-10,.
Section III. COMPONENT TESTING AND CALIBRATION
1. When possible, connect the two test leads to
6-7. Insulation Resistance Tests on Cables
opposite ends of the cable to avoid shorting.
2. To connect a test lead to a male pin of a cable
Use the megger to perform the insulation resistance
connector, adapt the alligator clip by
tests. Refer to the referenced schematic diagrams for
connecting it to a female pin of the correct
wiring of the cables.
size.
WARNING
3. To connect a test lead to a female pin of a
cable connector, adapt the alligator clip by
Test leads of Ohmmeter ZM-21A/U are at
connecting it to a male pin (or solid wire) of the
potentials up to 500 volts when the hand crank
correct size.
is being rotated. To avoid injury make all
connections when the hand crank is not being
a. Coaxial cables W13, W14/W15, W16, W21, W45,
rotated. DO NOT handle the test leads while
the crank is rotating.
(1) Connect the LINE terminal of the megger to
NOTE
the center contact of a plug.
To accomplish connection of the test leads
from the LINE and GROUND megger terminals
to the pin contacts of the cable connectors,
proceed as follows, whenever applicable.
6-3
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