Sidetone Check, Unmodified Maintenance Kit

TM 11-6625-1635-12

C h e c k . Start the equipment as instructed in

(1) Leave the AN/URM-43A connected

p a r a g r a p h 2-5 and proceed as follows:

as described in e a b o v e .

( 1 ) Connect Wattmeter, Radio Frequency

(2) Set the selector switch to PVT.

(3) Key the AN/ARC-134 with the U-

AN/URM-43A (fig. 2-5) to antenna connector

94A/U and talk into the microphone. Sidetone

J1 on the maintenance kit.

should be present in the headset and no power

output should be indicated on the AN/URM -

43A.

(4) Set the selector switch to position 1.

( 5 ) Repeat step 3. T h e r e should be no

sidetone and n o p o w e r i n d i c a t i o n o n t h e

AN/URM-43A.

(6) Set the selector switch to position 2.

( 7 ) Repeat step 3. T h e r e should be no

sidetone or power indication.

(8) Set the selector switch to position 3.

( 9 ) Repeat step 3 . S i d e t o n e s h o u l d b e

p r e s e n t , power s h o u l d b e i n d i c a t e d o n t h e

AN/URM-43A, and the meter on the main-

t e n a n c e kit should indicate changing current

levels.

Figure 2-5. Wattmeter,

Radio

Frequency

AN/URM-43A.

(10) Set the selector switch to position 4.

connected to maintenance kit.

(11) Repeat step 3. There should be no

sidetone or power indication.

(2) Set the VHF COMM frequency selector

(12) Set the selector switch to position 3.

switches (fig. 2-2) to 132.500 MHz.

h. Modulation Checks. Start the equipment

(3) Set the test panel PTT switch to ON. A

as instructed in paragraph 2-5 and proceed as

power output indication should be observed on

follow's:

the AN/URM-43A and, on the maintenance

(l) Leave the AN/URM-43A connected as

k i t modified, the dc ammeter should indicate

described in e a b o v e . O n the maintenance kit

between 6 and 9 amps.

u n m o d i f i e d , leave the M-52A/U connected to

the MIKE jack.

f. Sidetone Check, Unmodified Maintenance

(2) Set the AN/ARC-134 meter switch

Kit. S t a r t t h e e q u i p m e n t a s i n s t r u c t e d i n

( fig. 2-4) to MOD 1 10A FS.

p a r a g r a p h 2-5 and proceed as follows:

( 3 ) On the maintenance kit unmodified,

(1) Leave the AN/URM-43A connected

key the AN/ARC-134 with the M-52A/U

as described in e a b o v e .

switch. On the maintenance kit modified, key the

(2) Connect microphone M-52A/U to the

AN/ARC-134 with the U-94A/U. Talk into

test panel MIKE jack.

( 3 ) C o n n e c t the

H-216/U

the

the microphone and observe the AN/ARC-134

meter. T h e m e t e r s h o u l d f l u c t u a t e w i t h

SIDETONE jack.

modulation.

(4) Key the AN/ARC-134 with the M-

(4) Disconnect the H-216/U and M-

5 2 A / U switch and talk into the M-52A/U.

52A/U from the test panel of the maintenance

T h e A N / ARC-134 sidetone should be heard in

kit unmodified.

t h e headset. Release the M-52A/U switch.

g. Sidetone Check, Modified Maintenance

( 5 ) Connect Signal Generator AN/URM-

127 through a 50-f blocking capacitor (fig. 2-6)

Kit. S t a r t t h e e q u i p m e n t a s i n s t r u c t e d i n

to the test panel MIKE INPUT jacks (fig. 2-2).

p a r a g r a p h 2-5 and proceed as follows:

2-10