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
a. Oscillator V1. The oscillator is self-contained
5-1
