Looking to setup a mtn top repeater - low power. Retevis?

[N2MRG]

Hi all,
I've been on GMRS for 15+ years and amateur about as long. I am not very active. I am interested in putting a GMRS repeater on top of a private mountain with permission, with solar panels and lithium batteries to improve backcountry ski communication as well as dead cell zones on local roads.

I do not need it to be powerful because of the prominence over the surrounding area.

I see that the Retevis is Part 95E accepted. Will it work?

I have been reading the laws on cornell.edu and it does not look like station ID is required.

47 CFR Subpart E - Subpart E—General Mobile Radio Service

www.law.cornell.edu

Is a Time out timer required? I don't think the retevis has one....

Picking a frequency. IS there a frequency coordinator? I have looked on mygmrs and have not found a lot of nearby repeaters. Is there somewhere else I should be looking at?

 

[mmckenna]

It should work.

What they originally rolled out was a 10MHz split using small mobile type duplexers. 10MHz split won't work on GMRS, 2 meters, etc.
They added a version that would do closer spacing. You have to specifically request the GMRS model.

I don't own one, so I can't comment on that specific model. Knowing what I know, I'd be suspect of a repeater that small and how good the duplexer is. You can only make those things so small and have it work well. Since it's built around the low cost Chinese radios, I'd be concerned how well it would actually work with the limited filtering on the radios and a poor quality duplexer. Might be fine at a very quiet radio site. Probably going to totally suck eggs at any site with other high power repeaters.

If you do buy one, I'd love to hear how it works for you.


That said, I do have a network of low power repeaters at one of our sites that consists of high mountains and deep valleys. I "inherited" the site after they had an outsider build it, had it work very poorly, and then asked me to "fix" it.

The three sites consist of solar power, battery backup, 10 watt UHF repeaters. Each site is pretty much identical. The repeaters installed by the outside guy were the Bridgecom analog repeaters. With careful design, they work well. They'll normally do 40 watts, but these are cranked down to 10 watts to make the best use of solar power. 10 watts is plenty.
The sites are really remote. One was built with helicopters and pack mules. Two of the sites can be accessed by four wheel drive, the third requires packing test equipment/tools in on my back (I don't rate a helicopter ride).
High winds, freezing temps in the winter and blazing hot in the summer.
The system has worked out well. 10 watts is plenty for a repeater that is designed to work with hand held radios. 2 solar panels and a pair of 100a/h 12 volt gel-cells works well. Lithium batteries are nice, but might be overkill for what you need.

Anyway, back to your questions….

Station ID isn't required for the repeater. The end users need to ID. Still, it's not a -bad- idea to have it ID periodically. That really makes life easier if it starts causing interference to other repeaters. No, not required, but not a bad idea.

Time out timer isn't required by the rules. But again, a super good idea. It doesn't take much to get the repeater hung up. One of those units running TX for several hours is going to kill your batteries in short order. The heat build up could damage the repeater. In general, having some sort of time out timer on the repeater is a super good idea, especially with a low priced repeater that won't stand up to the abuse like a nice commercial quality unit would.

There is no GMRS frequency coordination group like there is on amateur radio. It really is pretty much a free for all.
But, as you can guess, you do want to do some work to make sure you are not causing interference to another user. Using sites like MyGMRS.com is a good place to start to see what's out there. Those sites do not include all the GMRS repeaters out there. The FCC databases won't show GMRS repeaters either. So the burden is on you to make sure your system doesn't mess with another repeater.


I'll add, that system I inherited, one of the big issues with the original design was poor antenna choice. The antenna is really important. If you are at a high site with deep valleys, putting up a high gain antenna isn't a good idea. Lower gain antennas can work much better in that sort of environment.

 

[cmdrwill]

Station ID and Time out timer for sure. And FCC Certified radio/repeater.

 

[N2MRG]

Thanks... The retevis97 is 95e certified. Yes that does surprise me, but it is.

 

[mmckenna]

Thanks... The retevis97 is 95e certified. Yes that does surprise me, but it is.

Yeah, that just means it meets the requirements for GMRS. Unfortunately it doesn't really mean much about it's quality.

 

[cmdrwill]

"retevis97 is 95e certified." for FRS. IF you like really funky audio AKA very narrow-band.

 

[mmckenna]

"retevis97 is 95e certified." for FRS. IF you like really funky audio AKA very narrow-band.

Yeah, I think with the odd narrow bandwidth, it'd sound like crapola on any real GMRS radio.

I know price may be a challenge, but the Bridgecom UHF repeaters can be had in a GMRS variant. You can turn them down to 5 watts and still have a pretty decent unit. You can get them with a flat pack mobile duplexer installed inside the case.
It's 19" rack mount, 2RU high, but you can stuff them in a cabinet.
They have a 12 volt input on the back, so you can hook them up to your battery/solar setup directly. Install and antenna, and you're on the air.

 

[R8000]

You get what you pay for. There are hundreds of other better options you could use that'd be better then a china repeater.

 

[jeepsandradios]

Lot of chatter on the mygmrs forum on this repeater. I have been planning to get one for my motohome to replace my GR1225 but to be honest been lazy. My 1225 works other than its a battery hog when we are dry camping. I since changed and only turn it on when we leave the RV vs it sitting on all night. A few guys where talking about setting a solor one up on a hill.

Agree on better for the money, but if power use is a issue I think this a is a good option.

 

[N2MRG]

"retevis97 is 95e certified." for FRS. IF you like really funky audio AKA very narrow-band.

You can run it in wideband, no? I believe it is a software setting(?)

 

[N2MRG]

Lot of chatter on the mygmrs forum on this repeater. I have been planning to get one for my motohome to replace my GR1225 but to be honest been lazy. My 1225 works other than its a battery hog when we are dry camping. I since changed and only turn it on when we leave the RV vs it sitting on all night. A few guys where talking about setting a solor one up on a hill.

Agree on better for the money, but if power use is a issue I think this a is a good option.

What else is out there for $400?
I see a lot of stuff out there that is like $600-800+ with no programming and of course no duplexer.

Power is definitely an issue and I suspect this thing will run well with like one 200 watt panel and a 25 ah battery.

 

[N2MRG]

You get what you pay for. There are hundreds of other better options you could use that'd be better then a china repeater.

For $400 though?

 

[jeepsandradios]

You can get a R1225 for under 400 if you shop, but not always with duplexer. You could use a couple 1225 mobiles and cheap flatpack duplexer with power supply also to get a to a $400 price. But also size may be a matter not sure. I have not seen any other repeaters that cheap on the used market.