190-00133-02 Rev B 3-8
3.3.3.8 Side Lobe Suppression
1. Set the
SLS / ECHO
toggle switch to the
OFF
position.
2. Adjust the RF level on ATC-1400A to MTL so that the XPDR%REPLY is 90%.
3. Raise the RF level to 3 dB above the MTL.
4. Set the
SLS / ECHO
thumb wheel switch to 0dB.
5. Flip the
SLS / ECHO
toggle switch to the
ON
position. The GTX 320 % Reply shall have an average reading
of 1% or less.
6. Raise the RF level on the ATC-1400A to MTL +50 dB. The GTX 320 % Reply shall have an average reading of
1% or less.
______ < 1% Reply (Average Reading)
3.3.3.9 External Suppression
With the unit replying to interrogations, apply a positive external suppression pulse of up to 100 microseconds
and with a voltage amplitude of greater than 8.0 volts. The unit must suppress the replies to any interrogations
received during the time of the suppression pulse.
______ OK
3.3.3.10 External Altittude Encoder Inputs
1. Set the digital oscilloscope to the following settings:
PARAMETER
SET POINT
EXT TRIG
CH 2 (XMTR Detected Video)
CH 2 VERTICAL SENS
20MV/DIV
HORIZONTAL SWEEP
5µS
DELAYED SWEEP
CENTER ON FIRST PULSE
2. Set the
XPDR MODE
switch on the ATC-1400A to position
C
. The oscilloscope shall display the P1 and P3
pulses similar to Figure 3-3.
______ OK
3. Rotate each of the four rotary switches on the GTX320 under test through at least one complete turn, stopping
on zero. The unit shall not transmit any code information as evidenced by a change in the P1 and P3 pulse
patterns. The XPDR CODE digital display on the ATC-1400A test set shall indicate 0000.
______ OK
4. Rotate the mode select switch on the GTX320 under test to the
ALT
position.
______ OK
