Antenna Circuit Analysis (FO 6-2, 6-3)

TM 11-5821-284-34

Figure 2-8. Servo motor and motor control logic, simplified schematic diagram.

base of Q15. Transistor Q15 conducts supplying a logic

the ferrite core produces a small variable series

"O" to CR19 and causing the coupler to tune toward

inductance used for fine tuning the antenna.

minimum capacitance of the antenna tuning capacitor

thereby increasing the resonant frequency of the

2-15.

Power Sources Analysis

antenna.

(Fo 6-2, 6-3)

The power required by the antenna is a +28-volt dc

2-14. Antenna Circuit Analysis (FO 6-2, 6-3)

source This +28-volt dc source controls three voltage

The antenna is a vertically polarized, folded monopole,

dividers for the operation of the antenna. A +5.1-volt dc

divider is used for logic functions, a +6.2-volt dc divider is

matched to the impedance of a 50-ohm transmission

used for a signal reference in the operational amplifier

line.

ARI, and a + 13.7-volt dc divider is used for gatlng

a. The antenna circuit is tuned by varying

functions.

series capacitance. Shunt inductor L4 matches the

antenna impedance with the impedance of a 50-ohm

transmission line when the antenna circuit is at

2-16.

Tuning Indicator Drive Analysis

resonance.

b. A small ferrite core placed around the

The tuning indicator drive supplies square-wave output

antenna uses the magnetic field generated by L1 and L2

pulses (nearly identical to pulses supplied

to change permeability. The change in permeability of

2-10