The idea is to have two antennas, four rigs, and be able to switch any rig to either antenna, at the same time connecting the other antenna to one of the other rigs.
Obviously it must not be possible to have two rigs connected to each other, nor to have both antennas connected to one rig at the same time.

What it will also be able to do is to switch a rig between two antennas with one switch action, or one antenna between two rigs with one switch action.

I want to use it on 2m, but not certain it the relays will be OK.
New inexpensive relays have short internal paths compared to those of 20 years ago, I decided to try it, and if it didn’t work, just to use it on HF.

 

Circuit diagram at the very bottom of the page

 

 

Well, it works!

In practical terms, if I transmit 45W through the first port on 145.0, and connect another radio to the second (adjacent) port, that is not switched through to an antenna, I get an S3 signal if it is tuned t 145.5, and an S7 signal on 145.00125.

The change to SWR measured at the rig is 1.05:1 going to just under 1.1:1

Much better than I had expected, there is a lot of wire in it

 

The toggle switches select which antenna that radio will connect to, and the rotary switches select which radio that antenna will connect to.

The toggle switch switches the ground to the relays, and the rotary switches the positive to the relays