Table 2-2. Relationship Between RF Tune Control and Operating Frequency

TM 11-5825-270-23

above. The rms voltmeter may be

the alarm volume is satisfactory.

connected directly across TB1 (1-2).

(25) Silence aural alarm by momentarily

pressing the ALARM SIL switch.

NOTE

(26) Using the multimeter, check the state of

The maximum output level at TB1 (1-

alarm contacts at TB1 (at rear of the unit): Contacts 5-4

2) is 250 mW. This equals 12.25 V

of TB1 must be open circuit and contacts 4-3 must be

rms into 600 ohms.

closed (shorted).

(27) Slowly turn SENSITIVITY control R7

(29) Close the front panel and turn the latch

clockwise until the CARRIER LEVEL meter reading is 1

so that it engages.

dB greater than the trip level set in (22) above. Check to

(30) Set power ON/OFF switch to OFF.

see that the receiver reverts back to normal operation

(NORM light on and ALARM light off). Now adjust R7 for

Table 2-2. Relationship Between RF Tune Control and

0 dB reading on the CARRIER LEVEL meter.

Operating Frequency

NOTE

When performing (27) above note

FREQUENCY

DIAL

FREQUENCY

DIAL

KHZ

SETTING

KHZ

SETTING

that receiver cannot revert back to

190

360

normal operation during the pause

200

370

between code transmissions. The

210

380

SENSITIVITY control R7 should

220

390

therefore be adjusted during the

230

400

keying sequence.

240

410

250

420

(28) Connect a 600 ohm, 1W resistor across

260

430

TB1 (1-2) and connect an rms voltmeter across the

270

440

280

450

resistor. Check that meter reads 12.25 V rms (0.1 V).

290

460

If this reading is not correct, adjust AUDIO LEVEL

300

470

potentiometer R14 on the IF PCB for 12.25 V rms

310

480

(0.1V) on the volt-meter.

320

500

330

520

NOTE

340

535

If TB1 (1-2) is terminated into a 600

350

ohm line, do not install the 600 ohm

1W resistor as specified in (28)

2-6