Transponder Set Test Set AN/APM-378,
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
Do not connect transponder output to RADIATED TEST unless an attenuator of 50 DB
minimum is placed between test set and transponder.
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.
1. Connect test set to power source. Turn POWER switch ON. Allow 30 seconds
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.
4. Select SYSTEM TYPE (type of transponder system under test) LOBINGor SINGLE
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.