One antenna for multiple radios

[dbljay7542]

I just purchased a new "Shack in the box" radio that has separate antenna connections for HF and VHF/UHF. I have another radio (2M/70CM) that is connected to a 2M/70CM antenna. What I am looking to do is to be able to connect the new radio to the 2M/70CM antenna without disconnecting it from the other radio. In a perfect world, the radios would not be used at the same time. I do not want to cause damage to the new radio by accidentally transmitting on the VHF/UHF side without an antenna load. Any ideas would be greatly appreciated. DI/TRIplexer?

 

[AK9R]

Di- and tri-plexers are used to keep various bands separate. For example, if you had one antenna that was designed to be used on both 2m and 70cm, you could use a di-plexer to route the 2m signals to one radio and the 70cm signals to another radio. But, routing in-band signals to two different radios would require a duplexer which is expensive and would have to be tuned to specific frequencies.

An antenna switch would be your best solution.

 

[K4EET]

^^^ What @AK9R said. Just be sure you don’t transmit on the radio that is without an antenna. You will also obviously not be able to receive on that radio either.

As for a good duplexer, since it is tuned to specific frequencies, you would be “locked in” on the two frequencies, one specific frequency for each radio.

Another option is to run another coax to another dual band antenna with adequate isolation to the existing antenna so you can monitor simultaneously with both radios and transmit anytime on either radio without having to flip a switch.

 

[mmckenna]

I do not want to cause damage to the new radio by accidentally transmitting on the VHF/UHF side without an antenna load. Any ideas would be greatly appreciated. DI/TRIplexer?

There isn't any easy way to do this that allows you to have full functionality of the radio. Duplexers are tuned and not going to give you full coverage on both bands with both radios.

You essentially have two options:

1. Discipline. Make sure you don't transmit with the wrong radio. It's not likely to 'blow up' the radio if it transmits into no load for a few seconds, but not a good thing to do with long winded ham conversations.

2. A switch. MFJ has gone out of business, but you may still be able to find one of these:

MFJ 1703B Antenna/Transceiver RF Safety Switch

MFJ 1703B √ Usually in stock

en.classicinternational.eu

Put a 50Ω load on one of the ports that is rated for whatever your radio puts out. The switch will allow you to switch radios. Output will either go to the antenna or to a 50Ω load (or another antenna).