Antenna Relay - distributor Box


Have you problem with your RG - cables ? Is it necessary too many cathodes from your Antennas to shack? This page describes a smart antenna box using "an RG-cathode for 3 antennas". The remote control needs just a simple wire and the GND for remote-control !

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FIG.1

The FIG.1 shows the Antenna-Box (on the roof) and the FIG.2 the control Box (shack).
The Antenna-box contains 2 relays. RL1 is activated by apllying positive voltage to it, where as RL2 needs negative voltage, depending on diode polarity.

In other words, if the control-wire is connected to possitive (+V) respecting to GND the RL1 is "on" and RL2 "off". If the wire-control is connected to negative (-V) the RL1 is "off" and the RL2 "on".
The GND (second cable) is the outer cable (shield) of RG-cable.


Table below shows the relation between S1-RL1-RL2 & ANT 1, 2, 3
S 1
Voltage CONTROL RL1 RL2 ANT-input to:
"Path" :
ANT1
O V
OFF OFF
ANT 1
1-2 (RL1)
& 7-8 (RL2)
ANT2
+ V (- to GND)
ON OFF
ANT 2
2-3 (RL1)
& 7-8 (RL2)
ANT3
- V (+ to GND)
OFF ON
ANT 3
8-9 (RL2)


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FIG.2

The Control-Box (FIG.2) includes just a rotary switch 2x3. Please, keep in mind: its absolutely necessary an independent Power-Supply for this Antenna-box. A small Power-pack (self plug-in)12-14 Volts / 200mA its enough.
DO NOT USE the same Power Supply with your other transceivers !!! (If the S1 switch turn-on to ANT3 we have "Short-circuit" between possitive and ground of PS ! That will be destroyed immediately the S1.)

RL1-RL2 are 12V relays and all diodes are 1N4004. C its a feedtrough capacitor (1nF) but if you havn't a feedtrough - don't worry about, it is not critical. Replace C by 2-3 ceramic cap's 1nF/63V in parallel.

My Antenna-Box has been costructed on a diecast alumin's box. I've used four female-chassis PL259 connectors for ANT-input & ANT 1, 2 ,3 output terminals.
The Control Box on my shack (including S1 rotary switch) is a small plastic box.

Finally, the wire connections between the contacts of RL1-RL2 have been designed in order to "Ground" the unused antennas. In other words, if the ANT1 is connected to the ANT-input (S1 to ANT1), ANT 2 & ANT 3 are connected to "Ground". If the ANT2 is connected to ANT-input (S1 to ANT2), ANT 1 & ANT 3 are "Grounded" etc.

That's all folks !

Have fun !

Makis SV1BSX
Jan 2002
backhombrew