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through the reference voltage
switching relay which is also
controlled by the multivibrator.
After a lapse of approximately 3
sec., the multivibrator causes the
RF switching relay to connect
antenna #2 to the receiver for a
period of 0.3 sec. During the
"sampling" period, the disabling
relay shorts the input of the bearing
indicator so that the indicator
pointer is not affected by the
sampling operation. At the same
time, the 30 cycle receiver output
is applied to the amplitude comparison
circuits where a DC voltage
proportional to antenna #2's output
is developed. If this voltage
does not exceed that stored from
antenna #1, the original cycle is
repeated and the reference voltages
are not switched. If, however,
antenna #2 provides the stronger
signal, the cycling operation is
reversed and antenna #2 becomes
the operating antenna, antenna #1
the sampled antenna and the corresponding
reference voltages are
switched to the indicator.
1
with Celco
miniaturization
Other System Components
A block diagram of the complete
local station is shown in Fig. 9.
A standard Air Force developed.
ground based, military UHF radio
receiver is used in the AN /CRD -6
for amplification and demodulation
of the D/F signal. The receiver is
designed to provide reception of
AM signals on any one of 1750
crystal controlled channels, spaced
at 100 KC intervals from 225.0 MC.
to 399.9 Mc, 10 of which may be
preset and selected automatically.
The receiver is a triple conversion
superheterodyne employing a crystal
synthesizer utilizing 38 crystal
units. These units provide the basic
frequency control for the full 1750
channels. The receiver has a 3
for a 10: 1 signal -tonoise
ratio.
Special design features are incorporated
in the receiver to provide
satisfactory performance when
used as part of the D/F facility.
A separate D/F detector and low
impedance cathode follower responsive
to 30 cycles are provided. To
minimize system instrument errors,
the 30 cycle phase shift resulting
from variations in signal amplitude,
modulation percentage changes, and
(Continued on page 196)
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Transistor Transformer
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Plug -in Transformer
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Encapsulated
Magnetic Amplifier
Designed and built to the most precise demanding specifications
of the Avionics industry, Celco components give better performance
with less weight and space.
1. Thin- gauged, grain- oriented nickel alloys yield improved
performance.
2. Glass, asbestos, silicone, and polyester film insulations
allow higher operating temperatures.
3. Latest epoxy and silicone rubber encapsulation
techniques highly developed at Celco.
Take advantage of the Celco design and production experience
in this specialized field ... call RAmsey 9 -1123 or write today.
MAHWAH, N. J.
Your plant is only hours away by the Celco Air Fleet
Tele -Tech & ELECTRONIC INDUSTRIES June 1956
For product information, use inquiry card on pages 209 -210. 195