Test Equipment Calibration

TM 11-5826-258-24

3-17. Test Equipment Calibration

30 percent modulation.

(5) Set the MD-83A/ARN FUNCTION SELEC-

All test equipment used in the bench tests must have a

TOR to CAL.

valid calibration sticker attached, and must be in prop

(6) Set the MD-83A/ARN SPECIFIC SIGNAL

er working order. The following adjustment pro-

SELECTOR to 30~ VAR.

cedures must be performed before performance of the

(7) Adjust the MD-83A/ARN 30~ VAR potenti-

test procedures.

ometer (inside the door on front panel) for 1.0 volt on

a. Power Supply PP-348/ARN Adjustment.

the OUTPUT meter.

(1) Connect Cable CX-1290/ARN to OUTPUT of

(8) Adjust the SG-1A/ARN MOD LEVEL control

power supply and to POWER INPUT of Signal Gener-

to read 30 percent on PERCENT MODULATION

ator SG-lA/ARN.

meter.

(2) Connect Cable CX-237/U to LINE INPUT of

(9) Set the MD-83A/ARN SPECIFIC SIGNAL

power supply and to 115-volt ac line.

SELECTOR to 9960FM.

(3) Set POWER switch to HEATER. Wait 5 min-

(10) Adjust the MD-83A/ARM 9960FM potenti-

utes.

ometer for 30 percent reading on SG-lA/ARN PER-

(4) Set POWER switch to ON. The power indi-

CENT MODULATION meter.

cator lamp should light. Wait 5 minutes for warmup.

(11) Set the MD-83A/ARN SPECIFIC SIGNAL

(5) Set INPUT VOLTAGE ADJUST switch to

SELECTOR to 90-150~.

NORMAL.

(12) Set the MD-83A/ARN TONE LOCALIZER to

(6) Needle on INPUT VOLTAGE meter should

CAL 90~.

read 115 volts ac 10 percent. If reading is incorrect,

(13) Adjust the MD-83A/ARN 90~ potentiome-

reset INPUT VOLTAGE ADJUST.

ter for 20 percent reading on SG-1A/ARN PERCENT

b. Signal Generator SG-1A/ARN Adjustment.

MODULATION meter.

(1) Perform Power Supply PP-348/ARN adjust-

(14) Note the exact reading on the MD-83A/ARN

ment procedures (a above).

OUTPUT meter so that the 150-Hz signal can be set to

(2) Set OSC SEL switch to MO.

the same point.

(3) Turn FREQUENCY to 112.0 MHz.

(15) Set the MD-83A/ARN TONE LOCALIZER to

(4) Adjust RF LEVEL for redline on RF MON-

CAL 150~.

ITOR meter.

(16) Adjust the MD-83A/ARN 150~ potentiom-

(5) Set OSC SEL switch to OFF.

eter for exactly the same reading on the OUTPUT

(6) Adjust METER ZERO (right side) until RF

meter as obtained in the 90-Hz adjustment.

MONITOR meter indicates 0.

(7) Set OSC SEL switch to MO.

(8) Turn FREQUENCY to 88.0 MHz.

3-18. Receiver Control Tests

(9) Adjust RF LEVEL for redline on RF MON-

a. Test Equipment Required. Multimeter

ITOR meter.

AN/USM-223, or equivalent, is required.

(10) Set MOD switch to 400~.

b. Frequency Switching. At the frequency settings

(11) Set MOD RANGE switch to 100 percent.

specified in table 3-4, check for specified ground or

(12) Adjust MOD LEVEL until PERCENT

open condition at the specified pine. Pin conditions

MODULATION meter indicates 100.

shall be as specified for frequency settings obtained by

(13) Set MOD switch to EXT.

both clockwise and counterclockwise rotation of con-

(14) Set OSC SEL switch to XTAL.

trol frequency selector knobs. Rear connector pins 27

(15) Set XTAL FREQ switch to 110.1 MC.

(16) Turn FREQUENCY to 110.1 MHz.

and 44 shall be connected to ground for this check.

c. Power Switching.

(17) Adjust RF LEVEL for redline on RI MON-

(1) With the control NAV VOL and MB VOL

ITOR meter.

knobs both set in the OFF positions, check for con-

(18) Set XTAL FREQ switch to 114.9 MC.

tinuity between rear connector pins 6 and 8, then pins

(19) Turn FREQUENCY to 114.9 MHz,

8 and 13. There must not be continuity.

(20) Adjust RF LEVEL for redline on RF MON-

(2) Move the NAV VOL knob clockwise out of the

ITOR meter.

c. Modulator MD-83A/ARN Adjustment.

OFF position and then check for continuity between

rear connector pine 6 and 8, then pins 8 and 13. There

(1) Connect the MD-83A/ARN MOD OUTPUT to

must be continuity between pins 6 and 8, but not be-

the SG-lA/ARN EXT MOD INPUT.

tween pins 8 and 13.

(2) Set POWER switch to ON.

(3) Move the MB VOL knob clockwise out of the

(3) Adjust the SG-lA/ARN MOD LEVEL control

OFF position and then check for continuity between

fully counterclockwise.

pine 8 and 13. There must be continuity.

(4) Set the SG-lA/ARN for full-scale reading at

3-6