DC POWER DISTRIBUTION.

TM 11-6625-2976-40

1-13. GENERAL. (CONT)

The rf modules receive operating voltage and modulating signals from their respective portions of the

circuit card assembly. Fixed or variable modulating signals are applied to the LOC, GS, or VOR

modules. Fixed modulation only is applied to the MB module. The rf modules then provide carriers

for the modulating signals.

The modulated rf output signals from the LOC, GS, and VOR modules are applied to the GS/VOR/LOC

antenna through an attenuation and combining network. The attenuators can be adjusted by controls

on the front panel to provide 0 to 110 db of attenuation. The MB rf output signal is fed through an impe-

dance matching network to the separate MKR BCN antenna.

The fixed or variable rf outputs of the GS/VOR/LOC antenna provide on-course or deviated-course

GS, VOR, or LOC indications for aircraft navigational systems. The fixed rf outputs of the MKR BCN

antenna provide outer marker, middle marker, or inner marker signals.

1-14. DC POWER DISTRIBUTION.

Refer to FO-3 while reading the following text.

Two 8-volt batteries provide dc power for all test set circuits. The batteries are series connected with a

common ground to allow + 8 volts and -8 volts application.

Dc power is applied from the batteries directly to circuit card (PCB) assembly A6 at J19. J19 connects

directly to J20, which makes battery power available at main power switch S2. S2 controls power to all

circuits In the test set.

In addition to S2, each modulating circuit and its accompanying rf module has Its own power switch.

These front panel switches make operating voltage available for each individual test set function.

When S2 is in the ON position, dc power is available at all front panel power switches (S6, S10, S15,

and S21). When any of these switches is also in the ON position, operating voltage is applied In the

following manner:

1. Through the controls in selected front panel section and J20 to appropriate circuit card

assembly modulating circuits.

2. Through J20 and by direct circuit card path through the P1 connector to the appropriate

rf module. (The P1 connections are Illustrated on FO-2 and FO-3.)

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