ANTENNA TUNING AND PROTECTION MODULE A1100.

TM 11-5820-670-30

1-22. ANTENNA TUNING AND PROTECTION MODULE A1100.

Frequency modulated rf signals from transmit/receive relay K4501 are fed through homer relay K4502

to the A1100 tuning circuits which consist of tuned tank circuits. The tuning circuits consist of an

band, 30 MHz through 52.95 MHz, and a

band, 53 MHz through 75.95 MHz. The gear train

selects band

, depending on the setting of tuning dials at the control unit. The resonant

frequencies of the tank circuits are varied by rotating the tuning dials, which alter the inductance and

change the overall LC ratio in the

and

frequency range.

The bandwidths of the resonant tank circuits allow passage of signals of the selected frequency while

unwanted frequencies are rejected.

The protection circuit has a neon lamp which shunts excess rf signal strength to ground. From the

protection circuit, rf signals are applied to tuning circuits in the first rf amplifier.

1-23. FIRST RF AMPLIFIER MODULE A1200.

Rf signals are amplified by the first rf amplifier, which consists of vacuum tube V1201. The amplified

signals are then fed to tuning circuits which function similarly to those described in the previous

1-22