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GMRS / FRS - Discussions related to GMRS (General Mobile Radio Service) and FRS (Family Radio Service) communications

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Old 06-13-2017, 5:55 AM
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Default Handheld GMRS Repeater?

I was up on a local mountain the other day on a random GMRS channel using the Baofeng GMRS V1. My buddy was about 18 miles away at his home and we could easily talk to each other mind you we where not using a repeater at all. I was extremely surprised I was able to hear him clearly (by the way we both have our GMRS licenses) so just theoretically speaking if I purchased 2 more GMRSV1's and purchased the little Baofeng repeater control box I think it's called SainSonic RPT-2D, and I used a GMRS repeater frequency that no one around me uses for example if I used 462.700 as my receive frequency and used a +5 offset input 467.700 and and for ex a PL of 77.0. So let's say I got this far and I put it in some box or something and put it in a tree or some location on that mountain where I heard my friend prior. Wouldn't I basically have a fully legal GMRS repeater? The only issue I see is the Repeater ID'er would be the only thing I would have to figure out a solution. Thanks!
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Old 06-13-2017, 6:32 AM
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Unless you are using a simplex "parrot" repeater, you will likely need a duplexer. Separate transmitter and receive antennas could be used, but they need to be spaced far and have low loss coax with an output radio being able to put out enough watts.
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Old 06-13-2017, 6:54 AM
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Quote:
Originally Posted by MASONROBERSONMR View Post
I was up on a local mountain the other day on a random GMRS channel using the Baofeng GMRS V1. My buddy was about 18 miles away at his home and we could easily talk to each other mind you we where not using a repeater at all. I was extremely surprised I was able to hear him clearly (by the way we both have our GMRS licenses) so just theoretically speaking if I purchased 2 more GMRSV1's and purchased the little Baofeng repeater control box I think it's called SainSonic RPT-2D, and I used a GMRS repeater frequency that no one around me uses for example if I used 462.700 as my receive frequency and used a +5 offset input 467.700 and and for ex a PL of 77.0. So let's say I got this far and I put it in some box or something and put it in a tree or some location on that mountain where I heard my friend prior. Wouldn't I basically have a fully legal GMRS repeater? The only issue I see is the Repeater ID'er would be the only thing I would have to figure out a solution. Thanks!
Yes, it's legit as long at the transmitting radio is Part 95a type accepted.

As pointed out, you immediately have an antenna/duplexer problem. Regardless of what radios you use, you can learn an awful lot about repeaters over on repeater-builder.com. And there's plenty of existing threads here about building repeaters. Again, the specific radio isn't nearly as important as the feed line, antennas, and duplexers.

Given that you're using low power portables, you'd lose a bunch of power in the duplexer. Something to think on. You may be better off staying simplex and improving your existing antenna.

Lastly, a repeater IDer is not required for what you envision. You can just ID when ever you use it, especially since you're comtemplating it as kind of a "just me and my buddy" sort of system.
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Old 06-13-2017, 6:58 AM
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Interesting feedback! This is something I would like to learn more about and something to possibly just to "fiddle with"
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Old 06-13-2017, 10:23 AM
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Are simplex repeaters legal? Also where do I get the controller box for them I have not been able to locate them.
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Old 06-13-2017, 11:06 AM
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My understanding from setting up GMRS repeaters 35yrs ago is the repeater must be FCC type accepted AS A REPEATER for Part 95A and not just the internal radios used for the repeater. In many services a repeater must meet tighter technical specs than just a radio used in the same service.
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Old 06-13-2017, 11:25 AM
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We used to use 2 HT-220 portables with their own batteries in a 4 in pvc pipe on ham channels located on mountain tops. We never needed duplexers, with the antenna's separated about 3 ft at each end of the pipe and with a suitable ground plane it worked fine. Just make sure you put the RX antenna at the top. We used to throw a rope up into a tree and pull it up about 30 ft and easily got 20 miles. Height is everything, with 1-5 watts you get pretty far.

35 years ago those channels were business channels and had a power limitation and that's it. I never saw anything in Part 95 lately that states you must use a Type Accepted repeater.
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Old 06-13-2017, 11:52 AM
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There may be other specifics buried in Part 95 rules, but here is one that pertains to GMRS repeaters and certain base stations. The way I understand it is the transmitter used in a GMRS repeater must be FCC type accepted as a Part 95 repeater and here is one specification called out for GMRS repeaters that is different than mobiles or hand helds:

(b) Each GMRS transmitter for mobile station, small base station and control
station operation must be maintained within a frequency tolerance of 0.0005%.
Each GMRS transmitter for base station (except small base), mobile relay
station or fixed station operation must be maintained within a frequency
tolerance of 0.00025%.

That would mean part of the FCC type acceptance for a GMRS repeater transmitter would include meeting 0.00025% frequency tolerance. That usually requires a high end TCXO or ovenized oslillator, something that most mobiles and hand helds usually do not have.
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Quote:
Originally Posted by radioman2001 View Post
We used to use 2 HT-220 portables with their own batteries in a 4 in pvc pipe on ham channels located on mountain tops. We never needed duplexers, with the antenna's separated about 3 ft at each end of the pipe and with a suitable ground plane it worked fine. Just make sure you put the RX antenna at the top. We used to throw a rope up into a tree and pull it up about 30 ft and easily got 20 miles. Height is everything, with 1-5 watts you get pretty far.

35 years ago those channels were business channels and had a power limitation and that's it. I never saw anything in Part 95 lately that states you must use a Type Accepted repeater.
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Old 06-13-2017, 12:44 PM
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So any narrow-band radio will do.
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Old 06-13-2017, 12:46 PM
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So any narrow-band radio will do. GMRS was exempt from narrow banding except for tolerance?
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Old 06-13-2017, 1:40 PM
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Three problems.

1. The lack of filtering (already pointed out).

2. The chinese radios do not have good selectivity or filtering in their receiver. As pointed out earlier with older Motorola HT's (that had a real receiver) it worked. However the budget radios on the market now have zero filtering. You will desense yourself.

3. Spectral purity. The chinese radios often have transmitters that throw illegal spurs all over the band when they transmit. Good duplexers will help suppress some of these, but you will be pissing off all your frequency neighbors if you go cheap.

The moral of the story is. do not use budget radios as repeaters. If you want to have the local public safety radio tech cussing you up a storm because he is trying to find the spur that keeps keying up one of his channels, then go for it. I can tel you this, because I was the public safety radio tech who had to hunt for a spur from a cheap, budget radio.

The moment you consider putting up a repeater for ANY service (GMRS, ham..etc), throw the idea away about using cheap radios. Your contraption may work for you, but if you are using budget radios you probably lack the knowledge that you are probably hurting other users close by to you in frequency with spurs.

Do yourself and others a favor and just purchase/acquire a used commercial repeater. Motorola, Vertex, Kenwood, Icom, Harris/GE/MA Com, EFJ....something from a known company who can make a transmitter operate within spec. You will be happy you did in the long run.

Good luck.
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Old 06-13-2017, 2:49 PM
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That's a bit much for a temp 1-5 watt homemade portable repeater. I agree even an old Micor is much better than using some Xinese crap as a real repeater. I don't believe the OP was talking about putting this repeater up in a high RF enviroment and it may qualify as a small base due to low power. The only problems I ever had in 30+ years of commercial repairs was someone using a Kenwood mobile as a paging base and it had problems so it was splattering from UHF to VHF. Plus I found it was unlicensed, so it went away overnight.
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Old 06-13-2017, 3:38 PM
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Well now you know where all the manufacturers test their bubblepack radios for range (just kidding). Actually, antenna height above average terrain (also known as HATT) is a much bigger factor than power for reliable range at VHF or UHF. Putting a repeater on the mountain may be a great idea, but a repeater is not just two radios 'slapped' together. First things first would be AC power (or equivalent). next on my list would be a good antenna/duplexer setup. The last piece would be a repeater with the parts designed to work together-including shielding and a 'tight' receiver front. No need for high power-you would likely find 10-25 watts would still make the repeater heard much father than it can receive.

In simple terms, your mountain is doing the same job as a tall tower-and the equipment should match.

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Old 06-13-2017, 5:17 PM
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The ham bands are for experimenting with repeaters made from scrap and junk, not GMRS or commercial bands.
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Quote:
Originally Posted by radioman2001 View Post
That's a bit much for a temp 1-5 watt homemade portable repeater. I
agree even an old Micor is much better than using some Xinese crap as a real repeater. I don't believe the OP was talking about putting this repeater up in a high RF enviroment and it may qualify as a small base due to low power. The only problems I ever had in 30+ years of commercial repairs was someone using a Kenwood mobile as a paging base and it had problems so it was splattering from UHF to VHF. Plus I found it was unlicensed, so it went away overnight.
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Old 06-14-2017, 7:29 AM
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GMRS is nothing more than unlicensed Ham, and I wasn't advocating anything like this equipment on commercial even though I have a 37+ year old Micor 225 watt station is service since new on "T" band.
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Old 06-14-2017, 1:01 PM
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All good information, too much to quote.

Great idea but as mentioned you'll need a duplexor, unless you physically separate the antennas. Seeing it is just a portable setup this could work not the best and considering that it's just cheap baofengs I wouldn't worry about the long term damage to the receiver front end. There will be some issues in static and de-sense but it should work.

Go on ebay the controller box can be had for $50 from China.

Now with all that said. Your post mentioned 'legal'. Since you are using one of the few BaoFengs that are type accepted, you are miles ahead of the 'illegal' simplex repeaters on FRS freqs out there, and yes there is a lot out there. I really wouldn't concern myself with the fact that it may be a grey area with the controller box.

Of course not sure about where you are at and what kind of licensed Hams (aka: FCC Nazi's) you have around there. For myself, I just make sure that I have no interference issues and my gear is properly working. Personally I spent a lot of money to be as compliant as possible. (Something some Hams around here laughed at).

As for the ID, not needed. Just continue identifying yourself.

I got raked over the coals for transposing my Call sign once. I made it clear that they could feel free to call the FCC and then I could personally show the FCC the 4 'illegal' FRS simplex repeaters run by licensed Hams, 2 of them under the auspices of it being used for C.E.R.T. As well as, all the licensed Hams using the GMRS frequencies at power levels far exceeding the FRS limits, since they don't feel they need a GMRS license because they have a HAM license.

Needless to say, they tend to leave me alone now. I'm still the talk of their clique though, in the sense they don't understand why I spent all that money to have FCC type certified equipment, when I could have gotten by for a fraction of the cost with cheap chinese non certified gear. The fact that I am running a full duplex repeater at 30 watts is probably the reason I wanted to cross the T's and dot the I's as much as possible.

The only thing I have cheap is a cheap duplexor ($100) for now and the system is seldom in that configuration. (My repeater uses a Yagi to pick up signals from another town 12 miles away and rebroadcasts them out of a 5.2 gain omni directional, my reason for even putting up the repeater was interference from buildings in town, not a problem at the other one horse town. So I have to use space separation and notch filters for now, (eventually looking in to combining the signal into both antennas and seeing how that performs, leaving me with a oblong radiation pattern for travel between the two towns)

Last edited by swen_out_west; 06-14-2017 at 1:35 PM..
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Old 06-14-2017, 1:27 PM
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Quote:
Originally Posted by wyShack View Post
Well now you know where all the manufacturers test their bubblepack radios for range (just kidding).
Cannot speak for other manufacturers, but we test our higher-end (i.e. longer spec'd range) units from Mt. Scott, OK.



We achieve acceptable comms at the stated range.
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Old 06-14-2017, 1:43 PM
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Quote:
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Cannot speak for other manufacturers, but we test our higher-end (i.e. longer spec'd range) units from Mt. Scott, OK.



We achieve acceptable comms at the stated range.
I still firmly believe that the advertised range of these radios are over exaggerated to mislead clueless consumers into buying them. They don't read the fine print. They buy them, they use them briefly until they figure out they are useless, then throw them in a junk draw or trash can. Easy money for the manufacturers.
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Old 06-14-2017, 2:52 PM
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Quote:
Originally Posted by radioman2001 View Post
GMRS is nothing more than unlicensed Ham...
Last I heard, licenses were still required in GMRS.
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Old 06-14-2017, 2:54 PM
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Yea but you don't have to take a test
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