68-MHz Oscillator Tuning Adjustment

TM 11-6625-467-34

test set on the bench so the power detector

30-megahertz oscillator card HV8 above the card

assembly on the rear subpanel (fig. 3-6) is

cage.

accessible.

d. Pull the shaft of interlock switch S12 to the

b. Connect the equipment as shown in figure

override position.

3-31.

e. S e t t h e P O W E R S E L E C T O R s w i t c h t o

c. Pull interlock switch S12 to the override

NORMAL.

position.

f. Set the CIRCUIT SELECTOR switches to

d. S e t t h e P O W E R S E L E C T O R s w i t c h t o

0473.

NORMAL.

g. Connect rf jumper cable W4 from the 30 MC

jack to RF VM1.

e. Connect power to the test set.

h. Push the PRESS TO TEST button and adjust

f. S e t t h e F R E Q U E N C Y S E L E C T O R - M C

the HIGH FREQ AMPL control for a reading of

switches to 50.00.

g. Set the CIRCUIT SELECTOR switches to

approximately 50 percent on the TEST METER.

i. Push the PRESS TO TEST button and adjust

6997.

h. Push the PRESS TO TEST switch and adjust

L1 on the 30-megahertz oscillator circuit card HV8

for a maximum reading on the TEST METER.

the 500 KC AMPL control for a reading of 30 per-

cent on the TEST METER.

3-33. 68-MHz Oscillator Tuning Adjustment

i. Set the CIRCUIT SELECTOR switches to

Perform the following procedures to insure that the

0097.

collector circuit of the 68-megahertz oscillator tran-

j. Set the POWER SELECTOR switch to HIGH

sistor is tuned properly:

VOLTAGE.

a. Remove the test set from the case.

k. Note the reading on the AN/URM-145.

b. Connector power to the test set and set the

NOTE

POWER switch to ON.

If the RF voltmeter reading is greater than

c. Using the module extender board, extend the

35 volts, reduce the setting of the 500 KC

68-megahertz oscillator circuit card HW2 above the

AMPL control.

card cage.

l. Using the chart in B, figure 3-31, determine the

d. Pull the shaft of interlock switch S12 to the

override position.

TEST METER reading that corresponds to the RF

voltmeter reading (k above).

e. S e t t h e P O W E R S E L E C T O R s w i t c h t o

NORMAL.

m. Adjust R4 on the RF detector subassembly

f. Set the CIRCUIT SELECTOR switches to

(A14) (fig. 3-6) for the TEST METER reading deter-

0563.

mined in 1 above.

n. Disconnect the equipment.

g. Connect RF jumper cable W4 from the 68 MC

jack to RF VM1.

3-35. General Support and Direct Support

h. Push the PRESS TO TEST button and adjust

Testing Procedures

the HIGH FREQ AMPL control for a reading of ap-

The self-check tests of table 4-1, Operator/Crew

proximately 50 percent on the TEST METER.

i. Push the PRESS TO TEST button and adjust

Preventive Maintenance Checks and Services in TM

L1 on the 68-megahertz oscillator circuit card HW2

11-6625-467-12 determine the acceptability of the

for a maximum reading on the TEST METER.

repaired AN/ARM-87. These self-check procedures

test the various internal power supplies for correct

3-34. RF Power Detector Adjustment

voltages and the internal oscillator for proper opera-

(fig. 3-31)

t i o n . If all the tests are satisfactory, the AN/

P e r f o r m the following procedures to adjust the

A R M - 8 7 can be considered to meet acceptable

power detector circuit:

d i r e c t support and general support inspection

a. Remove the test set from the case and set the

standards.

3-49