Table 2-5.1. Transponder Set Test Set AN/APM-378, Operating Instructions

TM ll-4920-296-14&P

Transponder Set Test Set AN/APM-378,

Operating Instructions

DIRECT TEST

Connect RF cable (25 feet) (W4) between DIRECT TEST (NORMAL) jack on test set and

transponder antenna jack. For diversity system, connect remaining RF cable

(25 feet) (W4) between DIRECT TEST (DIVERSITY) jack on test set and remaining

transponder antenna jack. Attach resistive load AT1 (2027369) to RADIATED TEST

jack.

CAUTION

Do not connect transponder output to RADIATED TEST unless an attenuator of 50 DB

minimum is placed between test set and transponder.

RADIATED TEST

Place test set 50 feet from aircraft antenna. Elevate test set above ground by

latching case to inverted cover. Aim antenna (arrow) at aircraft antenna.

Connect 6 inch antenna cable (W5) from the antenna to the RADIATED TEST ANTENNA

jack on the test set.

TEST INSTRUCTIONS

1. Connect test set to power source. Turn POWER switch ON. Allow 30 seconds

warmup.

2. Select LAMP TEST FUNCTION.

Note ACCEPT, REJECT, and CODE ZEROIZE lights on.

Activate TEST switch, note ACCEPT

3. Select SELF TEST FUNCTION for any mode.

light on.

4. Select SYSTEM TYPE (type of transponder system under test) LOBINGor SINGLE

CHANNEL.

5. Select FUNCTION mode and CODE to correspond with transponder under test.

Activate TEST switch. Note ACCEPT light on.

6. Activate SLS switch.

Note ACCEPT light on.

During FREQ/POWER tests CODE reference is inactive.

8. CODE A/B and VERT BIT 1 switches are active for MODE 4 test only.

Change 1

2-16.1