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transmitter synchros and resolver. These synchros should be zeroed n accordance with the procedures set forth in
paragraph 2 of this section.
D. SCHEMATIC DIAGRAM AND PARTS LIST - The schematic diagram for the Antenna Control Power Supply is
contained in Figure 5-21. The parts list is contained in Table 5-14.
15. DIRECTION FINDING DISPLAY SCOPE
A. GENERAL - The scope displays the antenna pattern in azimuth and is used for indicating the azimuth direction of
a received signal. Append I contains complete instructions applicable to the basic scope. Some modifications have
been added to the scope; they are described below.
B. DESCRIPTION OF MODIFICATIONS -The modifications added to the basic scope are shown in Figure 5-22.
This consists of the addition of four circuit cards and some interconnection wiring. The circuit cards are a modulator, two
demodulators. and a writing gun relay driver.
(1) Inputs to the scope are the AGC signal from the associated receiver and the resolver reference voltage. The
modulator produces a square wave output with amplitude proportional to the magnitude of the AGC signal (which in turn
is proportional to signal strength) and in phase with the resolver reference voltage.
(2) The resolver block is actually two resolvers, one in the Pedestal and one in the Antenna Control Power
Supply. The resolver in the pedestal is geared to antenna azimuth direction and is corrected for boresighting errors b)y
the AZ ORIENT resolver in the power supply. The two resolver outputs are proportional to the sine and cosine of the true
azimuth angle. These AC signals are demodulated to DC and applied to the X and Y deflection amplifiers of the scope.
(3) To avoid damaging the scope face with a spot burn when no signal is present, the writing gun is kept off until
a signal is present. The writing gun relay driver is adjusted to energize the WRITE-DON'T WRITE relay at an AGC level
just above zero signal level. When the relay is energized, the writing gun is enabled.
(4) Interconnection wiring changes are shown in Figure 5-23. The circuit boards are described in greater detail in
the following paragraphs.
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