Chapter 3. THEORY OF OPERATION

TM 11-5820-919-12

CHAPTER 3

THEORY OF OPERATION

contains the overall functional description of the radio set

3-1.

INTRODUCTION.

for transmit and receive operation, followed by a brief

description of each module. It supports the operator's

and organizational level of maintenance for unit

3-2.

This chapter contains the functional theory of

replacement.

Section II contains a functional block

operation of the radio set. The information is provided

description of each of the seven radio set modules to

to enable the operators and organizational maintenance

provide a more detailed level of understanding of the

personnel to understand the overall function and

radio set operation.

capabilities of the radio set.

Section I

SECTION I

OVERALL FUNCTIONAL DESCRIPTION

audio signals are routed through the control panel to the

3-3.

GENERAL.

modulator/demodulator. The Xmt Audio mixes with the

three LO signals sent from the synthesizer to produce a

3-4.

This section describes the overall function of the

single sideband Xmt RF output. The low power Xmt RF

radio set, and discusses the transmit and receive

is amplified in the power amplifier and routed through the

operation at the module level. It also briefly discusses

harmonic filter to remove transmitter harmonics. The

the function of each module.

filtered Xmt RF is then applied to the antenna, via the

antenna tuner for impedance matching.

3-5.

RADIO SET FUNCTIONAL DESCRIPTION.

3-9.

RECEIVE OPERATION.

The Rcv RF signal

3-6.

The radio set is a 2- thru 30-MHz single

from the antenna is routed back through the antenna

sideband (SSB) transceiver with a transmitter output of

tuner and is filtered by the harmonic filters to remove

20 watts. Operation can be either voice, cw, or coded

spurious signals.

The Rcv RF is then routed to the

data (depending on the audio device used) with

modulator/demodulator where it mixes with the three LO

automatic antenna tuning.

There are three levels of

signals sent from the synthesizer to produce the Rcv

frequency conversion between audio and rf in both

Audio output. The Rcv Audio is then routed through the

transmit and receive with two stages of intermediate

control panel to the handset.

frequency (if.) amplification and filtering. The radio set

consists of seven functional modules.

Five of the

3-10. CONTROL PANEL (Figure 3-2).

The

modules are housed in the receiver/exciter unit:

receiver/exciter control panel provides operational control

of the radio set. It couples voice or CW key from the

Control Panel

audio devices in use by the operator, and has controls

Synthesizer

for selection of frequency, volume, mode, and sideband

Modulator/Demodulator

(SB), and illumination of frequency readouts. Frequency

Harmonic Filter

Select and Sideband Select signals are routed to the

Power Supply

synthesizer, and the Frequency Select signal also to the

antenna tuner. Filter Select signals are routed to the

3-7.

Two functional modules are housed in the

harmonic filter. Volume control, mode select and Xmt

amplifier/coupler unit:

Audio are applied to, and Rcv Audio is received from, the

modulator/d -modulator. The control panel also

1. Power amplifier

2. Antenna tuner

3-8.

TRANSMIT OPERATION (Figure 3-1).

Input

3-1