TX Rx Switching

TX Rx Switching

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As do many other
collectors of old
radios, I was faced
with the dilemma of
how to switch
between several
receivers and
transmitters. I
found the Ameritron
RCS-10 almost ideal
for a four
receiver setup.

I designed the
RCS-10 many years
ago while
engineering for
Ameritron. The
Ameritron RCS-10 is
an eight-position
switch that uses BCD
control signals. The
simple basic control
head has a diode
matrix to output BCD
from 000 though 111
to select up to
eight antenna ports.
The RCS-10 has the
unique feature that
only one port can be
selected at any one
time, making it
impossible to
equipment on any

  A B C
1 0 0 0
2 1 0 0
3 0 1 0
4 1 1 0
5 0 0 1
6 1 0 1
7 0 1 1
8 1 1 1

Also notice that
ports 1 through 4
are selected when
line C is low, while
ports 5 through 8
are selected when C
is high.

By connecting
receivers to ports
1-4, and
transmitters to
ports 5-8, the
RCS-10 can be used
as an antenna
transfer relay and
radio selector.
Matching pairs of
equipmment are
connected to the
following ports:

Port Rig
1 RX1
2 RX2
3 RX3
4 RX4
5 TX1
6 TX2
7 TX3
8 TX4

BCD A and B
select the radio
pair, while BCD C
becomes the T/R
relay. Whenever C is
high, a transmitter
is connected to the

This leads to the
question, what if I
want to mix

My solution to
that is to have two
BCD control boxes
that are activated,
one for the
receivers and one
for the
transmitters. A
simple power
transfer relay
switches between the
control boxes.

In this case any
number of
transmitters and any
number of receivers
can be used, so long
as the total used is
8 pieces or less. I
current use this
system with five
receivers and three
transmitters. Dual
switch control boxes
are used, with
output wiring
paralleled to a
single relay box.

The T/R relay
control comes from a
12 volt SPDT relay
that applies power
to the receiver
selector box. When a
transmitter comes
on, I have a 120
volt sensing circuit
that activates the
transmitter relays.