Catching Range Test. - TM-11-5820-398-350037

not within 3.5 kc of 31.50 mc or until

Short

antenna

a frequency of 31.9.5 mc is reached.

Load characteristics

(7)

Record the last RT-505/PRC-25 frequency

-------------------

Minimum

Test frequency (mc)

voltage

setting that produced an AN/USM-26

Resistance

Capacitancee

(rms)

(ohms)

(uff)

reading within 3.5 kc of 31.50 mc.

------------ -- --

-- -- ----------

Adjust RT-505/PRC-25 to 31.50 mc and

(8)

26.1

30.00------------------

repeat the procedures given in (3) through

56.2

52.50------------------

(7) above except reduce the frequency

56.2

53.50------------------

setting for each successive step until the

61.9

75.00------------------

output frequency exceeds 3.5 kc of 31.50

mc or until a frequency of 31.00 is reached.

(11) Set the test assembly TRANSMITTER

Withdraw the decoupling tool and engage

(9)

CARRIER switch to ON and read the

the coupling.

RF voltage across the resistor of the

Adjust the RT-505/PRC-25 to 51.50 mc

(l0)

transmitter load with the ME-26B/U.

and disengage the coupling ((2 above).

The minimum acceptable reading is listed

(11)

Repeat the procedures given in (3), (4),

in the chart in (10) above.

and (5) above until the AN/USM-26

(12) Set the test assembly TRANSMITTER

reading produced is not within 3.5 kc of

CARRIER switch to OFF.

51.50 mc or until a frequency of 51.95 mc is

(13) Repeat the procedures given in (10), (11),

reached.

and (12) above at 52..50, 53.50, and 75.00

(12)

mc. Use the chart in (10) above to corre-

Record the last RT-505/PRC-25 frequency

that produced an AN/USM-26 reading

late test frequency, transmitter load, and

within 3.5 kc of 51.50 mc.

minimum acceptable voltage.

Adjust RT-505/PRC-25 to 51.50 mc and

(13)

(14) Remove the antenna load adapters and

repeat the procedures given in (3), (4), and

replace the screw in the corner of the whip

(5) above, except reduce the frequency for

ANT jack.

each successive step, check the AN/USM-

g. Catching Range Test.

26 for 51.50 mc 3.5 kc at each step, and

(1) Perform the catching range test with the

stop if 51.00 mc is reached. Record the

equipment connected in a standard trans-

limiting frequency.

mitter test setup (para 103 and fig. 79.8)

(14)

Withdraw the decoupling tool and engage

except set the HP-200AB output level to

zero and the RT-505/PRC-25 frequency

the coupling.

Evaluate the test results. At both test

(15)

to 31.50 mc. Set the RT-505/PRC-25

frequencies (31.50 and 51.50 me), the

upside-down for this test.

minimum acceptable catching range is 650

Caution: Check to see that the RT-505/

kc with at least 250 kc on each side of the

PRC-25 is set to a frequency ending in 50

test frequency.

( XX.50 ) when disengaging the coupling in

procedure in (2) below; otherwise the

h. Distortion Test.

coupling may become damaged.

(1) Perform the distortion test with the equip-

(2) Disengage the mechanical coupling finger

ment connected in a standard transmitter

(fig. 3, TM 11-5820-398-20) that disables

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

the crystal switching assembly from module

connect test cable No. 1 from test point

Al0 (para 104e(2)).

A23J3 to chassis ground. The ME-57/U is

(3) Adjust the RT-505/PRC-25 to a frequency

used as a receiver for this test.

50-kc higher than its current setting.

(2) Set the test assembly TRANSMITTER

(4) Set the test assembly TRANSMITTER

CARRIER switch to ON.

CARRIER switch to ON and observe the

(3) Tune the ME-57/U for minimum distortion.

frequency indicated by the AN/USM-26.

(4) Read the distortion on the TS-723A/U.

it should be 31.50 mc 3.5 kc.

Maximum allowable distortion is 10 per-

(5) Set the test assembly TRANSMITTER

cent.

CARRIER switch to OFF.

(5) Set the test assembly TRANSMITTER

(6) Repeat the procedures given in (3), (4), and

CARRIER switch to OFF.

(5) above until the AN/USM-26 reading is

TAGO 8344-A