TUNE INDICATOR Function Test

TM 11-6625-1702-35

F'igure 4-4. TUNE INDICATOR function test, waveform.

4-7. TUNE INDICATOR Function Test

(fig. 4-3)

a. Test Equipment and Materials.

(1) Power supply, 28-volt dc.

(2) Oscilloscope AN/USM-140A.

(3) Antenna Coupler, 437S-1/1A.

b. Test Connections and Conditions. Connect the test equipment as shown in figure 4-3.

c. Procedure.

Control

settings

Step

Performance

standard

No.

Test procedures

Test equipment

Equipment under test

a. Test set meter indicates

a. Adjust power supply to

1 a. Turn on power

a. Set METER FUNC-

27.5 ±1.3 volts dc.

supply and al-

obtain 27.5-volt indi-

TION switch to

low time for

28 VDC.

cation on power sup-

ply meter.

warmup.

b. None.

b. Turn on oscillo-

b. Rotate MV ADJUST

b. Connect MV OUTPUT

scope and al-

terminals to FL1 and

fully counterclockwise.

FL5 of antenna coup-

low time for

ler. Connect FL4 to

warmup.

ground (fig. 4-3).

NOTE

If antenna coupler 4375-1 is used, perform step 1c and skip 1d; otherwise, skip step 1c.

c. Should read open

c. Measure resistance

c. None.. . . . . . . . . . . . . . c. Turn off power. S2 to

circuit.

from J4-A to Gnd.

"OFF."

Should read <1 ohm.

S2 to "Decrease Freq." . . . . . . . . . Measure resistance

from P2-A to Gnd and

J4-A to Gnd.

Should read open

S2 to "OFF." . . . . . . . . . . . . . . . . . Measure resistance

circuit.

from J4-B to Gnd.

Should read <1 ohm.

S2 to "Increase Freq." . . . . . . . . . Measure resistance from

P2-B to Gnd and from

J4-B to Gnd.

Turn on power . . . . . . . . . . . . . . .. None . . . . . . . . . . . . . . . . . . . . . . .. None

d. Oscilloscope waveform is

d. Monitor motor pulsing

d. None . . . . . . . . . . . . . . d. Momentarily set MAN-

UAL TUNE switch

similar to that in figure

signal on oscilloscope.

4-4.

S2 to either IN-

CREASE FRE-

QUENCY or DE-

CREASE FRE-

QUENCY.

e. Repetition period of

e. None . . . . . . . . . . . . . . . e. None . . . . . . . . . . . . . . . . . . . . . . e. Increase repetition rate

motor pulsing signal is

of motor pulsing sig-

15±5ms.

nal by rotating MV

ADJUST until TUNE

INDICATOR illumi-

nates brightly.

4-5

Change 2