Mode 4 Receiver Sensitivity and Reply Video Adjustments Using AN/UPM-137A

TM 11-6625-667-45/NAVAIR 16-30APM123-2/TO 33A1-3-367-22

(2) MAIN and DELAYED SLOPE +

TRIG SEL panel

Switches: +.

DCD MODE SEL: OFF

j. Connect the AN/USM-281A A INPUT to

INT/DCD/EXT EXT

test points listed in the chart below. Adjust the

SIG GEN FUNCTION FIXED FREQ

control indicated until performance requirement

SIG GEN NORM/INTERLEAVE: NORM

is obtained.

SUM ATTEN: -6 DB

GATING panel

NOTE

PASS: 00

In order to observe the pulse at

INHIB: 00

A2TP2, it is necessary to continuously

b. Set and adjust the AN/USM-281A controls

operate the PUSH-TO-TEST switch.

as follows:

Adjust the oscilloscope sweep and delay control:

MAIN TIME/DIV .1 MSEC

as necessary to observe signal.

DELAYED TIME/DIV: As required to

observed indicated waveform

Pulse Width

EXT

10/EXT/INT/LINE: EXT

Test Point

Adjust Control

INT/AUTO/EXT/EXT

10: AUTO

A1TP1 . . . . . . . . . . ..A1R6 . . . . . . . . . . . . ..0.30.01

MAIN SLOPE +:+

A1TP2 . . . . . . . . . . .. A1R1l . . . . . . . . . . . ..0.30.01

A1TP3 . . . . . . . . . . .. A1R14 . . . . . . . . . . . .. 0.30.01

DELAYED SLOPE +: +

A1TP4 . . . . . . . .... .A1R17 . . . . . . . . . . . . .0.7 0.01

DIV DELAY: As required to observe in-

A2TP1 . . . . . . . . . .. A2R2. . . . . . . . . . . . . . 2692

dicated waveform

A2TP2 . . . . . . . . . . .. A2R7 . . . . . . . . . . . . .. 120.1

DISPLAY: ALT

A1TP5 . . . . . . . . . . .. A1R22 . . . . . . . . . . . . . 1507.5

A VOLTS/DIV 5

5.1-23 Mode 4 Receiver Sensitivity and Reply

B VOLTS/DIV 2

Video Adjustments Using AN/UPM-137A

c. Set and adjust the AN/UPM-15A controls

as follows:

a. Set and adjust AN/APM-27(V) controls as

TRIGGER SELECT:EXT

follows:

PULSE DELAY coarse control 10

(1) CONSECUTIVE REPLIES to 64.

PULSE WIDTH coarse control 10 #s

(2) REPLY MODULATION-SPACING

POSITIVE AMPLITUDE: Fully ccw.

PULSE 2 to 0.

d. Connect the equipment as shown in figure

(3) REPLY MODULATION-SPACING

5.1-11 and apply power to all equipment.

PULSE 3 to 0.

e. O n t h e A N / U S M - 2 8 1 A , a d j u s t D I V

(4) SYNC GAIN to mid position.

DELAY as required to observe reply pulse on B

(5) SYNC DELAY to mid position.

INPUT.

(6) REPLY MODULATION1X/2X to

f. On the AN/UPM-15A, adjust POSITIVE

AMPLITUDE for a 5 volt pulse on A INPUT,

b. Set test set controls as follows:

adjust PULSE WIDTH fine control for a pulse

(1) FUNCTION TO SYSTEM.

width of. 5

and PULSE DELAY fine control

(2) MODE to 4.

for a delayed pulse leading edge 3.5

from

(3) DIR. RAD to RAD.

leading edge of reply pulse.

(4) ISLS to OFF.

g. Adjust AN/TPM-25A SUM ATTEN dial

c. set AN/UPM-137A interrogator signal

for a reading of 9 dBm minus the 1090 MHz

s i m u l a t o r TRANSMITTER-XMTR FREQ

loss of cable 139526.

switch to XTAL.

h. Continually press the transponder test set

d. Set and adjust AN/UPM-137A rf signal

PUSH TO-TEST switch and adjust control

generator controls as follows:

A1R43 (fig. 8-43) for a just accept indication.

(1) OUTPUT ATTEN 0-100 dbm to. -6.

Increase the signal generator output level 3 dBm.

(2) TRANSITTERXMTR FREQ to

i. Set and adjust the AN/USM-281 as follows:

XTAL.

(1) Sweep Display Swtich: ALT

(3) TRANSMITTER-CW SOURCE to

EXT 1090 MHz.

5.1-32

Change 5