Alignment of Transmitting Set, Radio AN/PRT-4

TM 11-6625-937-12

3-7. Alignment of Transmitting Set,

Radio AN/PRT-4

(figs. 3-9 and 310)

a. Perform preparatory procedures given in paragraph 34c.

b. Check condition of the ID-1189/PR internal battery (para 33c). Replace battery if necessary.

c. Set the ID-1189/PR FUNCTION switch to XMTR-VFO. Set the AN/PRT4 CH-1-CH-2 switch to CH-1.

d. Plug the ID-1189/PR TEST PROBE into AN/PRT-4 test point TP 1 (fig. 3-9) and press the AN/PRT-4 TONE-

VOICE switch in the direction of the VOICE arrow. All AN/PRT4 alignment procedures are accomplished with the TONE-

VOICE switch pressed in the direction of the VOICE arrow.

e. Using the alignment tool, adjust AN/ PRT-4 C27 (fig. 3-9) for a center of ALIGN scale meter indication on the ID-

1189/PR. Adjust C27 clockwise if the new channel frequency is lower than the old frequency, or counterclockwise if the

new channel frequency is higher than the old frequency. One turn gives approximately a 1-megacycle change. At the

proper setting, a slight back and forth adjustment of C27 will cause the meter pointer to deflect back and forth between

the calibration marks on each side of the center of the ALIGN scale mark.

f. Set the AN/PRT4 CH-1-CH-2 switch to CH-2 and hold the TONE-VOICE switch in the direction of the VOICE

arrow. Adjust R36 (fig. 3-9) for a center of ALIGN scale meter indication in the same manner as the C27 adjustment in e

above.

g. Set the AN/PRT4 CH-1-CH-2 switch to CH-1. Remove the TEST PROBE from TP 1.

h. Set the ID-1189/PR FUNCTION switch to XMTR-RF. Continue to hold the TONE- VOICE switch in the direction of

the VOICE arrow. Adjust AN/PRTT4 C43 (fig. 3-9) for a maximum meter indication, and then turn C43 clockwise to

reduce meter indication to three-fourths of the maximum indication.

i. Adjust AN/PRT4 C45 (fig. 89) for a maximum meter indication.

j. Adjust AN/PRT4 C51 (fig. 89) for a minimum meter indication.

k. Adjust C43 for a maximum meter indication. Do not adjust C45 or C51 after this final adjustment of C43.

l. Repeat c through f above, and then proceed to m below.

m. Remove the AN/PRT-i from the ID-1189/PR XMTR ALIGN receptacle and reassemble the AN/PRT-4. Replace

the cover plate, antenna, battery, and battery case (TM 11-5820-549-12). Use the same battery that was plugged into the

ID-1198/PR XMTR BAT. receptacle.

n. Plug the ID-1189/PR antenna into the XMTR ANT jack (fig. 3-1). Fully extend the AN/FRT-4 antenna. Place the

AN/PRT4 CH-1-CH-2 switch to CH-1. Hold the AN/ PRT-4 1 to 2 feet from the ID-1189/PR antenna.

o. Set the ID-1189/PR FUNCTION switch to XMTR-ANT. Press the AN/PRT4 TONE- VOICE switch in the direction

of the VOICE arrow. Move the AN/PRT4 away or toward the ID-1189/PR to obtain at least a midscale meter indication on

the ID-1189/PR. Adjust an AN/PRT-4 loading coil (fig. 310) for a maximum indication on the ID-1189/PR meter.

p. Release the A.N/PRT-4 TONE-VOICE switch and lower the AN/PRT4 antenna. This completes the alignment of

new channels 1 and 2 of the AN/PRT-4. Write the new operating frequencies (not crystal frequencies) in the respective

blocks above the AN/PRT-4 paneled- marked positions of the CH-1-CH-2 selector switch.

3-8. Alignment Chart, Transmitting

Set, Radio AN/PRT-4

After becoming familiar with the procedures in paragraph 3-7, the following alignment chart may be used to permit more

rapid AN/ PRT4 alignment.

NOTE

Be sure a good BA-399/U is used in XMTR BAT. receptacle.

Change 5

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