Table 3-1. Operating Control and Functions

TM 11-S820-55-1 2

(2) Close-talk into the microphone, increasing the

relay trips, increase the ANTIVOX GAIN (R45)

VOX GAIN control setting until the vox relay just

setting to minimum point necessary to prevent the

operates. For vox operation, it is desirable to close-

speaker output from tripping vox.

It may be

talk the microphone to prevent background noise from

necessary to increase the VOX GAIN setting slightly

tripping the Collins KWM-2/2A into the transmit

after this ANTIVOX GAIN adjustment to compensate

function.

for the ANTIVOX gain.

(3) Set meter switch (8) to ALC. Increase the

NOTE

setting of the MIC GAIN control (4) to obtain S6

Do not use more VOX GAIN or ANTIVOX

average reading on voice.

GAIN than necessary to control vox operation.

(4) Leave the MIC GAIN control (4) as set in (3)

If the vox circuits transfer between words,

above. Leave the microphone in normal operating

increase the release time constant by turning the

position. Set the OFF-ON-NB-CAL switch (1) to

VOX TIME CONSTANT control (R43) (under

CAL, tune in the calibrate signal, and adjust the A.F.

top cover) clockwise. If less release time is

GAIN control

desired, turn the control counterclockwise

(5) Adjust the EXCITER TUNING control (6) for

an approximate 1,00-Hz beat note. If the vox

Table 3-1. Operating Control and Functions

Figure 3-4

Index

Control

Function

OFF-ON-NB-CAL-(S11)

OFF

Removes a.c. power from power supply.

Connects a.c. power to power supply.

Turns on accessory noise blanker when used.

CAL

Turns on 100-kHz crystal calibrator.

EMISSION (S9)

LOCK

Grounds key line for continuous output in cw mode at full power.

Used for tuning.

TUNE

Reduces pa screen voltage with series resistor, and produces cw

carrier for tune-up.

LSB

Selects LSB bfo crystal, and raises vfo frequency for LSB

operation.

USB

Selects USB bfo crystal, and lowers the vfo frequency for USB

operation

Selects USB bfo crystal, raises vfo frequency, and turns on tone

oscillator. Keyed tone is applied to balanced modulator

instead of voice signal.voice signal.

3 BAND (S2 through S8, S13)

Selects capacitors and crystals needed to tune transceiver to

desired 200-kHz band. S13 grounds a different pin on

J25 for each band for remote antenna selection.

MIC GAIN (R8, S10)

Controls audio amplifier gain for ssb operation, controls tone level

for cw operation.

A.F. GAIN (R92)

Controls receiving audio amplifier gain.

EXCITER TUNING

Controls all ganged slug tuned circuits in receiver and exciter

portions of transceiver.

P.A. TUNING (C150)

Resonates pa plate circuit to operating frequency.

Meter switch (S12)

PLATE

Measures pa plate current by measuring pa cathode voltage

changes.

GRID

Measures pa grid current.

ALC

Shows ALC action by measuring cathode voltage changes at

transmitter IF amplifier V4A.

INCR LOAD

Adjusts power amplifier output impedance level to match

transmission line impedance for maximum power

transfer.

R.F. GAIN (R84)

Controls gain of receiver-transmitter, RF amplifier, and receiving

IF amplifiers during receiving.

Zero set knob

Permits calibration of frequency dial.

Crystal board selector (S15)

Selects second bank of crystals for additional coverage and

(in KWM-2A only)

changes scale on BAND switch.

13 Vfo tuning dial

Selects the frequency to be added to the band frequency to

establish the transceiver operating frequency.

Inside cabinet VOX GAIN (R39)

Controls gain of vox amplifier for voice-controlled operation.

Inside cabinet VOX TIME CONSTANT (R43)

Controls held-in time of vox circuit

Inside cabinetNTIVOX GAIN (R45)

Controls level of antivox signal fed to vox circuit.

3-10