Revision A
T-48 90 008 026
2-8
2. Pull the snap ring located on the side of the coupler and slip the coupler onto the antenna to be
tested. The TAP-135 utilizes internal springs to maintain pressure on the antenna blade.
Ensure the EMI gasket is compressed and flush against the aircraft skin.
3. Conduct the required test. If incorrect readings occur, re-position and ensure a snug fit on the
antenna before attempting another test.
4. For diversity testing of dual antenna systems, a second Antenna Coupler (standard in the T-
48A) must be utilized to attenuate the signal from the opposing antenna. Place the second
Antenna Coupler over the additional antenna as described in step 2. The coupler will provide
over 20db of attenuation, which is sufficient to prevent the Test Set from receiving the
alternate antennas RF signal thus producing an accurate measurement.
1
2.9.3
Optional
Direct Connect Coupler (TAP-141)
The TAP-141 Direct Connect Coupler provides a means of connecting a transponder directly to the T-48
Test Set, thus providing an accurate means of checking transponder power, frequency, sensitivity, and
diversity measurements.
2
The TAP-141 supplies an attenuated path protecting the Test Set from the high
RF power associated with transponders.
1. Ensure power to the transponder is secured to prevent accidental transmission without a load
connected.
2. Connect the TAP-141
TEST SET
connector to the
ANTENNA
connector
located on the
front panel of the T-48 Test Set.
Connect this end to the T-48 T/S
Tel-Instrument
Electronics Corp.
Te
st Se
t
TAP-141
Direct Coupler T-48/T-49
UU
T
TAP-141
Figure 2-5
3. Connect the TAP-141
UUT
connector directly to the transponder antenna connector.
4. Conduct the appropriate tests.
5. When testing is complete, ensure to de-energize the transponder under test and re-connect the
antenna connection to your transponder to prevent accidental damage to your unit.
1
Measurements utilizing the Tap-135 Coupler are accurate to within ± 3dB.
2
Measurements utilizing the Tap-141 Coupler are accurate to within ± 2dB.
WARNING
The TAP-141 Coupler is labeled as to which end is connected to the Test Set and
which end to the UUT. Ensure the proper connections are made before testing the
UUT. If the proper connections are not observed, the Test Set and/or UUT may
require repair and calibration.
Connect this end to the Unit Under
Test (UUT).
