Rf Power-Measuring Circuit

TM 11-6625-601-34

through resistor R21 and capacitor C12 to the

J37 and J38 to contacts of relays K2 and K3,

base of emitter follower Q5.

respectively. From the contacts of relays K2 and

b. Incoming audio is applied, through VOL

K3, respectively. From the contacts of relays K2

control R4, resistor R22, and capacitor C13, to

and K3, the rf signal is applied through plugs

the base of emitter follower Q5.

P 1 3 and P14 to attenuators AT4 and AT6,

c. Audio from emitter follower Q5 is applied

respectively, which reduces the rf signal an

t h r o u g h capacitor C14 and terminal 78 to

additional 6 db. The attenuated rf signal (down

HEADSET jack 7.

12 db from the input of the signal) is then

routed,

t h r o u g h jacks J44 and J45 of

114. Rf Power-Measuring Circuit

attenuators AT4 and AT6, and the contacts of

(fig. 1-7)

relays K2 and K3, to home left J14 and home

The rf power-measuring circuit in the

right jack J13, respectively. The equal level of

TS-1967/ARC-54

consists

directional

the rf signal applied to jacks J14 and J13

coupler, a function selector switch, two calibra-

simulates an on-course heading. Setting HOME

tion potentiometers, and an rf power meter. Rf

S I M U L A T O R switch S1A (rear) to LEFT

applies ground through contacts 3 and 1 of

power applied to DIR COUPLER IN jack J3 is

routed through plug P1 to directional coupler

switch S1A (rear) to terminal 1 of relay K2.

DC1. From directional coupler DC1, the main

Relay K2 energizes, removing attenuator AT4

portion of the input rf power is applied through

from the circuit and connecting attenuator AT5

plug P2 to DIR COUPLER OUT jack J6. A small

in series with the output. The resultant rf signal

portion of the rf power, incident (output) and

applied to home left jack J14 is attenuated 9 db

reflected, is detected by the diodes in directional

instead of 12 db as before. This simulates a left-

coupler DC1, resulting in a dc voltage propor-

course heading. Setting switch S1A (rear) to

RIGHT removes ground from relay K2, causing

tional to the incident and reflected power levels.

K 2 to reenergize. G r o u n d is then applied

From directional coupler DC1, the dc voltage is

applied to contacts 6, 4, and 7, 5, respectively,

through contacts 8 and 10 of switch S1A (rear)

of POWER/VSWR switch S2. Setting switch S2

to terminal 1 of relay K3. Relay K3 energizes,

to FWD applies dc voltage proportional to the

removing attenuator AT6 from the circuit and

incident rf power level, through contacts 4 and

connecting attenuator AT7 in series with the

12 of switch S2 and power calibrate potentiome-

output. The resultant rf signal applied to home

ter RI, to RF POWER meter M1. (Potentiometer

right jack J13 is attenuated 9 db instead of 12

R1 is used to calibrate meter M1 for the proper

db as before. This simulates a right-course

heading.

reading of a known amount of input rf power.)

Setting switch S2 to REFL applies dc voltage

1-16. Power Distribution Circuit

proportional to the reflected rf power, through

(fig. FO-6)

contacts 5 and 1 of switch S2 and potentiometer

R1, to meter M1. Setting switch S2 to CAL

Operating voltage of +27.5 volts dc is obtained

applies dc voltage proportional to the incident

from an external power source. The +27.5 volts

rf power, through contacts 6 and 2 of switch S2

dc is applied through POWER 28V DC jack

and VSWR CAL potentiometer R2, to meter M1.

J32 to power circuit breaker CB1 in the test set.

(Potentiometer R2 is used to position the meter

From circuit breaker CB1, +27.5 volts dc is

needle to CAL.) Setting switch S2 to VSWR

various

circuits in

the

routed to

applies dc voltage proportional to the reflected

TS-1967/ARC-54,

the

SM-349/ARC-54,

the

rf power, through contacts 7 and 3 of switch S2

C-3835/ARC-54, the RT-348/ARC-54, and the

and potentiometer R2, to meter M1.

CU-942/ARC-54 or the CU-943/ARC-54.

a. Routing of Voltage in Test Set, Radio

115.

Test Set,

Radio TS-1967/ARC-54

TS-1967/ARC-54. Closing circuit breaker CB1

Homer Signal Circuit

applies +27.5 volts dc to pin a of CONT UNIT

(fig. 1-8)

jack J16, pin 2 of lamp DS1, and contacts 10 and

7 of TEST FUNCTIONS SELECTOR switches

The homer signal simulator circuit in the test

S11D (rear) and S11F (front), respectively.

set consists of two relays, three 6-decibel (db)

With switch S11 set to TEST SET, +27.5 volts

attenuators, two 3-db attenuators, and a func-

dc is routed to terminals 11 through 15 of termi-

tion selector switch. An rf signal applied to

nal board TB1 from contacts 8 and 5 of switches

HOME INPUT jack J1 is routed through plug

S11D (rear) and S11F (front), respectively. The

P20 to attenuator AT3. Attenuator AT3 reduces

the rf signal 6 db and applies it through jacks

+27.5 volts dc applied to terminal 10 of TB1 is

1-17