Chapter 5. FUNCTIONING OF EQUIPMENT

TM 11-6625-2629-14&P

CHAPTER 5

F U N C T I O N I N G OF EQUIPMENT

Section I. GENERAL

5-1. Introduction

and is mounted on top of the chassis. It provides

a signal to mix with the incoming radio frequency

The modulation meter is essentially an fm

(rf) signal. The modulation meter input frequency

receiver which is used to measure deviation and

i s covered in five ranges selected by the

carrier shift of frequency modulated signal

FREQUENCY RANGE-MC switch,

generators and transmitters. In brief it operates

b. Mixer CR1. The mixer is mounted on the

by converting the incoming radio frequency

back of the oscillator. A crystal diode is used to

signals to a controlled-amplitude (adjustable

mix the radio of signal with the oscillator signal.

limited) intermediate frequency, employs a

The resulting intermediate frequency (if) signal is

d i s c r i m i n a t o r to detect the modulation (or

fed to the if amplifier/limiter section consisting of

deviation), a precision divider network to provide

wide measurement range, an adjustable-gain

VI, Ul, V7, and V8.

amplifier to drive output circuits, and power

amplifiers to drive a deviation meter and audio

output jack.

5-2. Block Diagram Description

(fig. 5-1)

a. Oscillator V1. The oscillator is self-contained

5-1