VHF and UHF repeater on same antenna

[iceman977th]

Long story short, our club has a 2 meter analog repeater on air currently. We are planning on setting up a UHF DMR repeater, but for the time being I'm hoping to use a diplexer and the existing antenna to get it on the air until we can put up a dedicated feedline for the UHF repeater. Our antenna is a dual band, and tested 1.5:1 I believe on UHF, so we should be good there. MY question is.. has anyone used two repeaters with a diplexer? Is it possible, or if they both transmit do I risk frying everything? In theory, I should be fine, but looking for real world experience (mind you, this is only temporary)

 

[dlwtrunked]

Long story short, our club has a 2 meter analog repeater on air currently. We are planning on setting up a UHF DMR repeater, but for the time being I'm hoping to use a diplexer and the existing antenna to get it on the air until we can put up a dedicated feedline for the UHF repeater. Our antenna is a dual band, and tested 1.5:1 I believe on UHF, so we should be good there. MY question is.. has anyone used two repeaters with a diplexer? Is it possible, or if they both transmit do I risk frying everything? In theory, I should be fine, but looking for real world experience (mind you, this is only temporary)

The RVARC repeater, here in Fredericksburg, VA, last year added a Fusion repeater running UHF analog and Yaesu digital to our VHF operation which using the same dual-band antenna with a diplexer. No problems were noted (including no impact on the existing VHF coverage) and things are working fine. This is why they make dual-band antenna like that.

 

[buddrousa]

2 things will have to happen.
1st is you will have to put up a dual band antenna.
2nd you will have to install a duplexer in the radio shack to isolate the repeaters like linked below just do not exceed total power levels.

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[kayn1n32008]

Buy a commercial diplexer(not a hammy grade one) that has N connectors, and ensure the combined power output of BOTH repeaters does not exceed to antennas rated power rating of the antenna.

 

[prcguy]

I had to install a low power low level UHF repeater at a site where the owner also wanted to use his shore station marine radio. We used a Comet GP-9NC and a ham grade diplexer. I worked quite well with no interaction and minimal impact if any on the repeater performance.

I would not use these components on a remote mountain top site and instead would use a commercial antenna rated for the needed frequencies and a commercial diplexer as mentioned.

 

[buddrousa]

As you know most people want a CC antenna $59 to work like a $2000 DB420 antenna

 

[bill4long]

if they both transmit do I risk frying everything?

Not a problem transmitting on both bands at the same time using a diplexer, as long as the transmit power does not exceed the rated TX power for each band, and does not exceed the overall rated TX power. I would leave a bit of head room in any case for both bands and combined power. And a commercial grade diplexer is definitely a good idea for a remote installation.

 

[k6cpo]

Long story short, our club has a 2 meter analog repeater on air currently. We are planning on setting up a UHF DMR repeater, but for the time being I'm hoping to use a diplexer and the existing antenna to get it on the air until we can put up a dedicated feedline for the UHF repeater. Our antenna is a dual band, and tested 1.5:1 I believe on UHF, so we should be good there. MY question is.. has anyone used two repeaters with a diplexer? Is it possible, or if they both transmit do I risk frying everything? In theory, I should be fine, but looking for real world experience (mind you, this is only temporary)

My club tried that and it didn't work very well. We finally put up a separate antenna for each repeater. They are both on the same tower with a bit of vertical separation. You should get that second antenna up as soon as possible.

 

[iceman977th]

My club tried that and it didn't work very well. We finally put up a separate antenna for each repeater. They are both on the same tower with a bit of vertical separation. You should get that second antenna up as soon as possible.

That's our goal.. we're just going to wait until warmer weather to install the second antenna (I have Heliax for both the 2m and the digital repeaters).. I've also considered Bridgecom's dual repeater duplexer setup but I had to resort to their Facebook group to get an answer on if it would work or not.. so not too impressed with their customer service.

 

[dlwtrunked]

My club tried that and it didn't work very well. We finally put up a separate antenna for each repeater. They are both on the same tower with a bit of vertical separation. You should get that second antenna up as soon as possible.

We had absolutely no problems and so have others. You guys probably did not have something tuned right or had poor components.

 

[prcguy]

I agree, if the antenna was in good condition and the diplexer was operating within its limits AND the UHF frequency was not exactly a 3rd harmonic of the 2m frequency, then it should work fine and only have a few tenths of a dB extra loss from the diplexer.

We had absolutely no problems and so have others. You guys probably did not have something tuned right or had poor components.

 

[bill4long]

My club tried that and it didn't work very well. We finally put up a separate antenna for each repeater. They are both on the same tower with a bit of vertical separation. You should get that second antenna up as soon as possible.

I agree with the others. I've used dual band antennas with repeaters and diplexers and always have had an excellent result. Something was amiss with your set up.