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Multiple radios on single antenna

Posted: Tue Nov 25, 2008 11:04 am
by jasong224
Please forgive me if this is a relatively dumb question, but what would the most efficient way be to share a single antenna and primary feed line with two VHF base station radios? Currently the two radios are older MaxTracs operating at 25 watts. Both radios are on the same frequency. (155.XXX)

Any suggestions?


Thanks,

Jason

Re: Multiple radios on single antenna

Posted: Tue Nov 25, 2008 6:25 pm
by ai4ui
If both are operating simplex then you can't reasonably isolate one transmitter from the other if they are operating on the same frequency.

Simple solution, use one radio & DC or tone remote to the other operating position. Even better, tone remote to them both so both operators can hear what the other one is saying.

Re: Multiple radios on single antenna

Posted: Wed Nov 26, 2008 8:05 am
by jasong224
Thank you for your reply,
I honestly am not really familiar with this radio and documentation is being hard to come by, everything I have learned about it has come from two sites, this being one of them.
For the proposed solution would I need a third radio?


Thanks,
Jason

Re: Multiple radios on single antenna

Posted: Wed Nov 26, 2008 9:22 am
by jasong224
By the way these only have the 5-pin accessory connector on the back.


Jason

Re: Multiple radios on single antenna

Posted: Thu Nov 27, 2008 4:54 am
by Jim202
Not wanting to ask a dumb question, but why would you ever want to run 2 radios on the same antenna
on the same frequency? I must be missing something here.

Been in the radio field for better than 40 years now and have never heard of anyone trying to do this.

Maybe if you explained what your trying to accomplish, you might have some good suggestions come
out of the woodwork.

Jim


jasong224 wrote:Please forgive me if this is a relatively dumb question, but what would the most efficient way be to share a single antenna and primary feed line with two VHF base station radios? Currently the two radios are older MaxTracs operating at 25 watts. Both radios are on the same frequency. (155.XXX)

Any suggestions?


Thanks,

Jason

Re: Multiple radios on single antenna

Posted: Thu Nov 27, 2008 5:52 am
by jasong224
The current system is operated out of an office type environment, currently there is a single radio in a relatively central location. The desire is to have a second radio located in an adjacent room. For ascetic reasons we were hoping to not have to install another outdoor antenna and a second feed line. I know I have seen passive devices for different frequencies, but never for anything closer than maybe 100KHz let alone the exact same frequency. Now under normal conditions the radios operate in a duplexed mode through a repeater, (TX: 155.XXX RX: 158.XXX) when the repeater is down or unreachable they use the talk around frequency of 158.XXX.

I hope this clears a few things up.
Maybe I am missing something big and am going about this in the entirely wrong direction, if so please help steer me to the correct path.


Thanks,

Jason

Re: Multiple radios on single antenna

Posted: Thu Nov 27, 2008 7:09 am
by Tom in D.C.
Wouldn't the easiest way to do this be to install a second, remote, microphone and an
extension speaker, both in the "other" room?

Re: Multiple radios on single antenna

Posted: Thu Nov 27, 2008 7:24 am
by jasong224
I suppose that would work, but I don’t think the radio in room A would hear the transmissions of the remote console in room B or the inverse is that incorrect?

Thanks,

Jason

Re: Multiple radios on single antenna

Posted: Thu Nov 27, 2008 8:12 am
by ai4ui
Put the radio in an out of the way location (so no one messes with it) & then tone remote it to the two operating positions.

Accessing the talk-around channel will be difficult to accomplish with the radios only having a 5 pin connection. You may want to look for a GM300 or one of the newer waris mobiles that have channel steering available from the acc. connection. You could then set up a function tone on the remotes to force it to the talk-around channel and back to the home channel.

Your vendor should be able to help you with this as long as you are able to specifically tell them what you are wanting to do.

Re: Multiple radios on single antenna

Posted: Fri Nov 28, 2008 12:02 pm
by jasong224
After reviewing some information and talking with one of our area reps we are going to go with a newer radio (CM200 / CM300) and remote stations.

I guess the MaxTracs will just go back into storage, I didn’t foresee using them very long since we are going to be changing over to narrowband operation eventually anyway.


Thanks for the information,

Jason