CHAPTER 3 OPERATING INSTRUCTIONS - TM-11-6625-922-150011

TM 11-6625-922-15

CHAPTER 3

OPERATING INSTRUCTIONS

3-1. Controls, Indicators, and Jacks (fig. 3-1)

Control, Indicator, or jack

Function

POWER (2-position toggle) switch

Controls primary power to TS-2669/GCM.

POWER ON indicator

Lights to indicate ac power is on.

1 AMP fuse

Protects ac input line.

RECEIVE LEVEL DBM (7-position rotary) switch

Attenuates input signal fed to input amplifier. Indi-

cated number corresponds to level in dbm. Minimum

attenuation is at setting of -40.

TRANSMIT LEVEL DBM (4-position rotary) switch

Controls output signal level. Indicated number corre-

sponds to power level in dbm. Maximum output level

is at setting of +10.

TRANSMIT LEVEL DBM control

Provides fine adjust for output signal level. Between

0 and 10 db can be added to level set by 4-position

TRANSMIT LEVEL DBM switch.

BAL RECEIVE jack

Accepts telephone-type plug for application of balanced

input signal, terminated in impedance between 130

and 900 ohms.

75 Ω UNBAL RECEIVE jack

Accepts BNC connector for application of unbalanced

input signal, terminated in impedance of 75 ohms.

(5-position rotary) switch

Selects terminating impedance for input signal. With

RECEIVER IMPEDANCE

75 (ohms) setting, 75 Ω UNBAL RECEIVE jack

must be used. With other 4 settings, 130 to 900

(ohms), BAL RECEIVE jack must be used.

MODULATION FREQUENCY HZ (3-position rotary)

Selects modulating frequency in Hz. Note that 83 1/3

switch

number is in red; this means that when switch is in

this position, red numbers on instrument are to be

used, instead of black numbers. Black numbers are

used with modulating frequencies of 25 or 250 Hz.

MOD FREQ ADJ control

Adjustable control for varying modulating frequency in

end-to-end mode of operation. Frequency can be

changed up to 50 parts per million (PM).

% MOD ADJ control

Adjust control for varying percentage of modulation

between 0 and 50 percent. This should always be set

for a nominal 50 percent modulation.

dbm/% MODULATION meter

Measures percentage of modulation or signal level in

dbm, as selected by % MOD/RECEIVE LEVEL/

TRANSMIT LEVEL switch. To determine correct

signal level, meter indication must be added algebrai-

cally to RECEIVE LEVEL DBM or TRANSMIT

LEVEL DBM switch setting number. If meter reads

-6, and RECEIVE LEVEL DBM or TRANSMIT

LEVEL DBM switch is set to -10, correct level is -16

dbm. If either switch was set to +10, then correct level

would be +4 dbm. TRANSMIT LEVEL DBM and

RECEIVE LEVEL DBM switches should be set so

that dbm/% MODULATION meter reading is always

between 0 and -10 dbm.

% MOD-RECEIVE LEVEL-TRANSMIT LEVEL (3-

Selects which parameter dbm/% MODULATION

position rotary) switch

meter will measure.

3-1