[ARC5] Command Set Antenna Relay Series Capacitor Use

[Henry Frederick "Meils" Meiseles]

I have two BC-342A units, one contains a

             WESTERN ELECTRIC CO.
                   PART NO. 8047
            50 MMF   5KV  5AMP.
MADE BY GENERAL Electric CO. U.S.A  19C3

The relay casing/cabinet 
US
has a ca. 3/4" high, red  "MI" below a ½" red square;       seems to be 
6094   inside (hardly legible)
both immediately to the right of the riveted label. 
A

SERIAL  NO 39579


I remember buying this on "Radio Row," in Manhattan around 1957.


My second BC-342A
has a somewhat larger label , attached with Philip-head screws

SERIAL NO 94***

"SC4668A in aprox. 1/4 red   color, parallel with and to the immediate right 
of the label.
(*I'm being nonspecific about the serial number because I was given this as 
a gift by a friend and fellow
vintage mil surplus buff, here in DK.)

Hope this is relevant in this thread..

/Henry, Cph.
  oz3o  n2nr


----- Original Message ----- 
From: "Mike Morrow" <kk5f at earthlink.net>
To: "ARC-5" <arc5 at mailman.qth.net>
Sent: Saturday, June 18, 2011 1:34 PM
Subject: [ARC5] Command Set Antenna Relay Series Capacitor Use


>> 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
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