Fig. 1-1. FM/AM Modulation Meter ME-505/U

TM 11 6625-3017-14

SECTION 1

GENERAL INFORMATION

1.1 INTRODUCTION

The TF 2300A Modulation Meter is primarily for

normally made by means of the meter readout, i. f. and

measurement of f.m. deviation but it also measures a.m.

demodulated outputs are available at the front panel for

depth. With its wide range of deviation frequency,

examination or analysis.

modulation bandwidth and carrier frequency, this

instrument is suitable for application to fixed and mobile

Spurious a.m. and f.m. due to hum and noise are

point-to-point communications, broadcasting, telemetry

kept to a level insignificant for most applications but,

and multi-channel link equipment in the h. f., v. h. f.

where required, crystals can be switched in to control the

and u. h. f. bands. Distortion and channel separation

local oscillator, or an external local oscillator may be

tests on f.m. stereo receivers and transmitters can also

used. The instrument can be operated without a local

be made.

oscillator for measurements in the 1-2 MHz range.

Positive and negative f.m. deviation can be

The instrument can be operated from mains power

measured in ranges from 1. 5 kHz to 500 kHz full- scale

or a nominal 24 V battery. Voltage regulation eliminates

at modulation frequencies between 30 Hz and 3.4 kHz

transformer tap changing except between 115 V and 230

on the 1.5 kHz deviation range, and 30 Hz and 200 kHz

V ranges. On battery, the regulation compensates for

on all other deviation ranges. A.M. depth can be

battery voltage variations between 21.5 and 30 V.

measured up to 95% in a 30 Hz to 15 kHz modulation

Transistorized circuits consuming little current give

bandwidth. Either f.m. or a.m. can be measured in the

reasonable length of operation on battery for mobile

presence of the other. Although measurements are

purposes.

Fig. 1-1. FM/AM Modulation Meter ME-505/U

1-1