VAR LAMP FLASHER CAPABILITY.

TM 11-6625-2976-40

1-17. RF MODULES AND RF DISTRIBUTION. (CONT)

Operating voltage and modulating signals are applied from circuit card assembly A6 to the rf modules

through feed-through connectors mounted on base plate A8.

VOR, LOC, AND GS RF MODULES

The output frequencies of the VOR, LOC, and GS modules are determined by front panel frequency

control switches S12 and S18 in the following manner:

1. LOC/GS frequency control switch S12 selects matched frequencies 334.70 MHz(GS) and

108.10 MHz (LOC) or 334.55 MHz (GS) and 108.15 MHz (LOC) as output frequencies for LOG

rf module A4 or GS/UH F rf module A2.

2. VOR frequency control switch S18 selects 108.00 MHz or 108.05 MHz as the output for VOR rf

module A5.

S12 and S18 apply positive or negative voltage to LOC rf module A4, GS/VHF rf module A3, and VOR rf

module A5. The polarity of the applied voltage determines the output carder frequencies of the mod-

ules. When positive voltage is applied, the GS/LOC modules output will be 334.55/108.15 MHz and

the VOR module output will be 108.05 MHz. When negative voltage is applied, the GS/LOC modules

output will be 334.70/108.10 MHz and the VOR module output will be 108.00 MHz. These carriers are

modulated within their modules by the modulating frequencies produced by the circuit card assembly

GS/UHF rf module A2 receives the unmodulated output of GS/VHF module A3 through a coaxial cable.

GS modulation is applied to the GS/UHF module only.

The rf outputs of the VOR, LOC, and GS/UHF rf modules are applied through coaxial cables and T-

connectors CP1 and CP2 to attenuators AT1 and AT2. The attenuator applies from O to 110 db before

passing the rf signal to VOR/LOC/GS antenna jack J3, from which it is radiated through the antenna.

MB RF MODULE

When a MB front panel selector switch (S3, S4, or S5) is pushed, it routes a modulating signal (para

1-16) to MB rf module Al, and the module generates an appropriately modulated 75 MHz carrier.

The rf output is applied through the impedance matching network in module A7 and MB antenna jack J1

to the separate MB antenna for radiation.

1-18. VAR LAMP FLASHER CAPABILITY.

Refer to FO-7 while reading the text in this section.

The GS, LOC, or VOR variable mode is selected by depressing lamp/switch S23, S24, or S25 respec-

tively. When depressed, the switch contacts transfer positive voltage, thereby changing the voltage

path and initiating the lamp flashing function. The three modes (GS, LOC, and VOR) use the same

lamp flashing circuit, but control different signal paths. The signal paths have already been dis-

cussed in paragraph 1-16. Therefore, this paragraph will cover only the common lamp flashing

clrcuit.

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