LAMP TEST MODE

TM 11-4920-296-14&P

module, and processes these signals. If the

output rf pulse during the self-test mode to

frequency and power of the reply pulses are

be fed directly through the receiver circuits,

correct, the REPLY SAMPLE output occurs

to develop a REPLY SAMPLE pulse (one for

from the if. video module and is fed to the

each interrogation pulse. . in that mode).

digital circuits (U3-TP10). During diversity

transponder testing, steering signals are

2-55. LAMP TEST MODE. To insure that

applied to the logic circuits of the if. video

all "result indicator" lamps of the test set

module; if the if. pulses are not received

are operative, the FUNCTION switch is

on the line that transmitted the strongest-

placed in the LAMP TEST position. This

signal, the if. video module circuits inhibit

action applies an input to the evaluator U4

any REPLY SAMPLE output. Thus, replies

stages controlling the ACCEPT and REJECT

received from the wrong output of the trans-

lamps, to cause both lamps to light simul-

ponder will cause a REJECT indication.

taneously at this time. The front panel

switch also supplies a ground path to the

2-52. During side-lobe operation, an SLS

CODE ZEROIZE lamp to make it light.

pulse input (U4-TP1) to the if. video module

circuits is processed to produce an output

to the rf microstrip module, and causes

2-56. POWER SUPPLY CIRCUITS. The

attenuation of the side-lobe pulse of any in-

test set can be operated from either ac or

terrogation pulse set (side-lobe pulse as

dc power sources, by means of the two

types of power cables, and its two POWER

switches. AC power must be in the range

tude of the other interrogation pulses). If

side-lobe operation is not in effect, the SLS

of 103.5 to 126.5 V ac, at frequencies of

pulse input is disabled, and all interroga-

50 to 70, or 380 to 420 Hz. DC power for

tion pulses are transmitted with the same

the test set must be 25.0 to 31.0 V dc.

amplitudes.

Figure 3-6 shows the schematic diagram of

the power supply circuits of the set. For ac

2-53. During diversity operation, circuits

power operation, the input voltage is applied

of the if. video module, in response to ALT

t o a step-down transformer/bridge-

CHAN GATE input from the digital section,

rectifier/filter circuit as shown. The output

provide the actual steering control signals

dc voltage is then applied to two integrated-

to the rf microstrip module, to alternately

circuit voltage regulator stages; these same

direct strongest (6 dB difference) interro-

stages receive the dc input power during dc

gations to first the NORMAL and then the

operation.

DIVERSITY. Simultaneously, the steering

signals are applied to the logic circuits of

2-57. The integrated circuit voltage regu-

the if. video module, to enable them to

lator stages produce outputs of +12 V dc (at

determine if the replies are received from

330 mA, 0.1 percent regulation) and +5 V

the correct diversity output.

dc (at 600 mA, 0.1 percent regulation) that

are applied to the solid-state circuits of the

2-54. Although not specifically mentioned

test set, and to the indicator lamps as

during the previous discussions, the trans-

shown. The regulator stages contain inter-

mitter oscillator circuits and the receive

nal current-limiting, thermal-shutdown,

LO circuits are not simultaneously gated-on.

and safe-area compensation capabilities.

These oscillators are controlled by the

INTERR and VIDEO GATE inputs to the rf

2-58. T h e dropping-resistor in series

module, respectively; the INTERR inputs

with the +5 V dc regulator minimizes the

occur during the encode cycle and the

differential voltage across the regulator

VIDEO GATE inputs occur during the

stage. A series-dropping resistor is con-

decode cycle. During self-test mode how-

nected in the dc power input line, to drop

ever, a VIDEO GATE input occurs to enable

that voltage to the same range as the dc

the receiver circuits of the rf module

output produced by the rectifier/filter

simultaneously with INTERR inputs to its

circuits (during ac power operation).

transmitter circuits. This then allows each

2-14