Electrical Tests. - SB-740-91-010264

SB 740-91-01

4.0 Electrical Tests.

The following tests are to be performed, using the applicable data sheets (figure B-21), for the Radio Set AN/ARC-51

series.

Step

Settings and Instructions

Normal Indication

Pressurization Check

With the RT-742/ARC-51BX and RT-742B/ARC-51BX

Pressure loss shall not

covers in place, pressurize with air to 6 psi.

exceed 4 psi.

Check pressure after standing for 24 hours

at the same temperature and altitude.

Transmitter Tests

For Receiver-Transmitter RT-742/ARC-51BX,

use procedure (a); for Receiver-Transmitter

RT-742B/ARC-lBX, use procedure (b). Use an

RF Wattmeter AN/URM-43A or equivalent in

place of an antenna. Unless otherwise specified,

use "VOL" and "SENS" controls in the maximum

position only.

(a) Turn on the radio by setting the power

switch on the control to the T/R position.

Allow the set to warm up for approximately 5

minutes before beginning the tests.

(b) Connect the equipment as shown in figure B-18,

and allow a 5 minute warm-up period. The RT-

742B/ARC-51BX has a duty cycle of 5 minutes

transmit and 10 minutes receive. During trans-

mit operation, observe this duty cycle ratio.

Connect the VTVM (ME-30/U) on the ilO V scale to

A6J2, turn the control head frequency to 399.9

MHz on the power amplifier. Key the transmitter

and adjust C6-Z1, C12-Z2, and C18-Z3 on the RF

preamplifier for maximum voltage on the VTVM.

Next connect the VTVM to A6J3, and adjust C5-Z1

trimmer on the power amplifier for maximum vol-

tage. Adjust C14-Z2 trimmer for maximum power

out and unkey. Connect the VTVM with the posi-

tive lead to A6J7 and the negative lead to A6J6

on the power amplifier with the transmitter un-

keyed.

CAUTION

There is 420 volts on A6J6 and J7 with respect

to ground while the transmitter is keyed. The

VTVM must be isolated from ground.

B-76