TM 11-5826-225-35
angular position of the resolver rotor
with respect to its stator windings and
relative bearing of the radio station,
determines the phase and amplitude
o f RF signal a p p l i e d to first RF
amplifier Q1. Resolver 133 driving
b e a r i n g synchro transmitter B4 is
part of a closed-loop servo system.
During adf operation, servo motor B5
runs B3 in one direction or the other
u n t i l the servo loop error voltage
drops to a minimum. At this point
resolver B3 will stop on a null.
(2) Before reaching second RF amplifier
Q3, the RF signal output of Q1 passes
through a 90-degree phase shift net-
work which insures that the loop an-
tenna and sense antenna RF signals
will be in phase or 180 degrees out of
phase. The RF output of amplifier Q3
is coupled to balanced modulator CR15
and CR16. Modulation is supplied by
two phases of 110-cps signals derived
from 110-cps oscillator Q22. The bal-
anced modulator output signal, applied
to a sense antenna signal mixing net-
work in push-pull RF amplifier Q2
and Q4, is a double-sideband signal
containing upper and lower 110-cps
sidebands with the RF carrier absent.
After adding the sense antenna RF
1-3
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