Transmitter System Tests, Radio Set AN/PRC-25

75.40, 75.50, 75.60, 75.70, 75.80, and 75.95

(9) Repeat the procedures given in (7) and

mc.

(8) above except increase the RF output

70 db to determine the 70-db-down

(6)

Repeat frequency check ((5) above) in

points. The 70-db-down points should be

reverse order (75.95 mc first).

Turn the megacycles control from 75 to 53,

less than 120-kc apart.

(7)

(l0) Search 50 kc beyond the 70-db-down points

then back to 75, and repeat the procedures

given in (2), (3), and (4) above.

for spurious responses. Detected spurious re-

Return the RT-505/PRC-25 to 75.00 mc,

sponses should not be above the -70-dblevel.

(8)

Note. The receiver system tests are now

set power supply A to 2.25 volts, power

completed. Perform the procedures indicated in

supply B to 10.00 volts, and repeat the

paragraph 103 before proceeding.

procedures given in (2) through (5) above.

Return the RT-505/PRC-25 to 75.00 mc,

(9)

105. Transmitter System Tests, Radio Set

set power supply A to 3.0 volts, power

AN/PRC-25

supply B to 15.00 volts, and repeat the

procedures given in (2) through (5) above.

a. Power Output Test.

(l0)

Evaluate the test results.

(1) Perform the power output test with the

Maximum

acceptable frequency inaccuracy is 3.5

equipment connected in a standard trans-

kc for all tests.

mitter test setup (para 103 and fig. 79.8),

except set the HP-200AB output level to

c. Tone Oscillator Frequency and Modulation Tests.

zero and the RT-505/PRC-25 frequency to

(1) Perform the tone oscillator frequency and

30.00 mc.

modulation tests with the equipment con-

(2) Set the test assembly TRANSMITTER

nected in a standard transmitter test setup

CARRIER switch to ON.

(para 103 and fig. 79.8) except set the

(3) Record the frequency and power output

HP-200AB output level to zero, connect

indicated by the AN/USM-26 and AN/

test cable No. 6 from the AN/USM-26

URM-43A respectively.

input to the ME-57/U audio output, and

(4) Set the test assembly TRANSMITTER

set the AN/USM-26 for a 10-second count.

CARRIER switch to OFF.

(2) Set the test assembly TRANSMITTER

(5) Repeat the procedures given in (2), (3),

CARRIER switch to ON.

and (4) above at 42.00, 52.95, 53.00, 65.00,

(3) Record the deviation indicated by the

and 75.95 mc.

Minimum

ME-57/U and the frequency indicated by

(6) Evaluate the test results.

the AN/USM-26.

acceptable power output is 1.6 watts on

(4) Set the test assembly TRANSMITTER

the low-frequency band (30.00 to 52.95 mc)

CARRIER switch to OFF.

and 1.1 watts on the high-frequency band

(5) Evaluate the test results. Acceptable

(53.00 to 75.95 me).

deviation is 3 kc 0.5 kc and acceptable

b. Frequency Accuracy Test.

frequency is 150 cps 1.5 cps (in a 10-

(1) Perform the frequency accuracy test with

second count).

the equipment connected in a standard

transmitter test setup (para 103 and fig.

d. Modulation Capability and Deviation Tests.

79.8), except set the HP-200AB output

(1) Perform the modulation capability and

level to zero., and the RT-505/PRC-25

deviation tests with the equipment con-

frequency to 75.00 mc.

nected in a standard transmitter test setup

(2) Set the test assembly TRANSMITTER

(para 103 and fig. 79.8), except set the

CARRIER switch to ON.

RT-505/PRC-25 frequency to 47.00 mc,

(3) Record the selected frequency (from the

ground A23J3 with test cable No. 1, and

R T - 5 0 5 / P R C - 2 5 REC-TRANS FRE-

adjust the HP-200AB output (and, as

QUENCY indicators) and the output fre-

required, the TRANSMITTER AUDIO

quency as indicated by the AN/USM-26.

INPUT LEVEL control for a 1.4-millivolt

(4) Set the test assembly TRANSMITTER

reading on the ME-30A/U.

CARRIER switch to OFF.

(2) S e t the test assembly Transmitter

(5) Repeat the procedures given in (2), (3),

CARRIER switch to ON.

and (4) above at 75.05, 75.10, 75.20, 73.30,

TAGO

8344-A