[ARC5] Command Set Antenna Relay Series Capacitor Use

[Mike Morrow]

> Further, the original designers supplied a vacuum capacitor with the
> antenna changeover relay (BC-442, RE-2 / ARC-5) with instructions in 
> the operating manual for connecting it in series or parallel with the
> antenna feed to match other impedances than that presented by a short
> airplane antenna.

That capacitor is intended for ONLY ONE situation:  Use of the 7 to 9.1 MHz
transmitter in installations where the command antenna is too LONG for that
frequency range.  In that instance, the antenna connection would be routed
to one end of the capacitor instead of to the TR (transmitter) terminal on
the antenna relay.  The other end of the capacitor would be connected to that
TR terminal, where the other transmitter(s) in the command set are also
connected.  Thus, for that transmitter ONLY, the capacitor would be in series
with its output.

The BC-442-AM model of antenna relay was manufactured without this capacitor
for those installations that did not use the BC-459-A transmitter, or for
installations such as fighter aircraft where the antenna was never going to
be too long electrically, even at 9 MHz.

Thus, this capacitor was never used for antennas that were too short.  Also,
use of this capacitor for multiple transmitters, or in a parallel arrangement,
was not part of the command set design.

Mike / KK5F