Section IV. OPERATOR'S MAINTENANCE INSTRUCTIONS

TM 11-5820-554-12

set to 14.296 MHz and the EMISSION switch on the

2/2A tuning dial. The VFO switch may then be

KWM-2/2A set to TUNE, the transmit circuits may

changed to REC 2-XMIT 2 position, and the Collins

be peaked and the pa loaded. The EMISSION switch

312B-5 dial adjusted to another selected frequency

is then set back to the desired sideband or CW, and

within the same band. Transceiver operation may

the Collins KWM-2/2A dial tuned to a desired

then be changed instantly from one frequency to the

receiving frequency between 14.3 and 14.350 MHz

other by operating the VFO switch on the Collins

(table 10-3).

312B-5 back and forth between the two positions

b. With the VFO selector switch in the REC 1-

marked REC 1-XMIT 1 and REC 2-XMIT 2. This

XMIT 1 position, both the receiver and transmitter

action permits presetting to a net frequency and a net

frequencies are the same and are controlled by the vfo

QSY frequency, and the instant selection of either

in the transceiver.

during net operation. Frequency separation limits

c. With the VFO selector switch in the REC 2-

listed in table 10-3 should not be exceeded by any

XMIT 2 position, both the receiver and transmitter

great extent. If they are exceeded, the result is

frequencies are the same and are controlled by the vfo

decreased receiver sensitivity or transmitter pa grid

in the Collins 312B-5. The vfo dial in the Collins

drive (or both) due to the selectivity of the transceiver

312B-5 can be calibrated in this position using the

RF tuned circuits. The best compromise for this tuned

crystal calibrator signal and zero set knob as outlined

circuit attenuation effect is to tune and load the

in paragraphs 3-9 through 3-13. With the Collins

Collins KWM-2/2A at a frequency midway between

312B-5 VFO switch set in REC 1-XMIT 1 position,

the two desired frequencies and then set the Collins

the Collins KWM-2/2A may be tuned and loaded to

312B-2 and Collins KWM-2/2A dials to the required

one selected frequency within the legal amateur band

frequencies.

using the Collins KWM-

Table 10-3. Collins KWM-2/2A and Collins 312B-5 Approximate Vfo Frequency Separation Limits

Band (M Hz)

3.4-4

7-7.4

14-14.4

21-21.6

28-30

Approximate limit of separation between Collins 312B-5 and Collins

KWM-2/2A dials.

15 kHz

30 kHz

50 kHz

75 kHz

100 kHz

Section IV. OPERATOR'S MAINTENANCE INSTRUCTIONS

10-10. General

Operator's maintenance instructions are covered in paragraph 3-19 through 3-22.

Cleaning is covered in

paragraph 3-24.

10-11. Operator's Preventive Maintenance Checks and Services Chart for Controls, Radio Set

C-6118/FRC-93 and C-75151/FRC-93

B-Before

A-After

M-Monthly

D-During

W-Weekly

Interval

Item

Item to be inspected

Procedure

Equipment is not

No.

ready/available if:

Equipment performance

Check operation of VFO with

Frequency fails to track or

transmitter on dummy load

lacks stability once tuned

using frequency counter.

to fixed frequency.

Change 6

10-9