Although ham radio offers a wide array of bands to transmit on, not to mention plenty of modes to communicate with, not everyone wants or needs to use all of this capability. For those needing simple two-way communication services like FRS or GMRS are available (in North America) with much less stringent licensing requirements, and GMRS even allows repeaters to be used to extend their range beyond the typical mile or so. [Dave] aka [N8DAV] has built an off-grid simplex repeater that can travel around with him wherever he goes.
The repeater itself is based on a pre-built simplex repeater module, which means that it has to record an incoming signal and then play it back on the same frequency. Compared to a split frequency repeater which uses different frequencies for transmit and receive this can be a bit cumbersome but simplifies the design and the use. A Baofeng UV-5R is used to perform the actual radio duties paired to a 40 watt amplifier to extend the range as much as possible. It’s all packed into a Pelican-like case and set up with a large battery that could power it for a number of days, making it useful for camping, rescue, or other off-grid activities.
For those wondering why [Dave] is using his ham call sign instead of his GMRS one, all of the equipment in this build will work in either the UHF ham bands or the channels reserved for GMRS with minor adjustments, so it’s perfectly possible to use the setup for one’s preferred license. And, for those in other parts of the world without GMRS there’s a similar class of radio called UHF CB which might be able to support similar builds, but be sure to check your local jurisdiction’s laws before hooking something like this up. For an even longer-range radio repeater using similar equipment we’d recommend looking to the skies.
Thanks to [Red] for the tip!
methinks the Australian Communications and Media Authority would have words to say about someone lashing a Baofeng UV-5R up to a 40W power amp as a way of home-brewing a UHF CBRS repeater.
If you don’t like it, don’t use it, but don’t ruin other peoples lives by being a snitch.
Amen
I can’t snitch on a repeater that isn’t here. Don’t bring it this side of the Pacific ocean.
Fortunately N8DAV is a US resident where a 40W amp on GMRS is perfectly legal, the article even makes it clear that you should “be sure to check your local jurisdiction’s laws before hooking something like this up.”
And thanks for proving my theory about people who use ‘methinks’ unironically.
40W on GMRS may be perfectly legal in the US, but I can guarantee you the spurs coming out of the Baofeng amplified aren’t. Many Baofengs are in violation of FCC rules out-of-the-box, with no amplification. This project needs a tight filter or tuned circuit between the Baofeng and the amp.
noob here – i had the impression that most amps function implicitly as a bit of a filter all on their own? like, specifically, i thought driving harmonic frequencies was usually the result of a flaw in the amp?
i glanced at the youtube and it’s a baofengtech amp, specifically designed for this purpose. so worse than spurious sidebands: it’s not a hack! but you can look up the amp, it’s been characterized a little bit already. it’s apparently a consumer product designed to meet the requirements, and not some general purpose tool released with just a prayer that you won’t point it at your feet. i have no idea if that’s good or not.
Yes, most amps have filters. They don’t solve the problem if the spurious signals are too strong however, particularly if they are within the same band, they may be amplified as is.
The amp only knows you’re trying to send a signal within a given frequency range and will amplify things in that range, they don’t know your trying to transmit on frequency X.Y and filter everything outside of the intended bandwidth.
This is also why adding an amp with poor equipment can be a violation in itself.
You feed an amp garbage, all it can do is amplify that garbage. What you get is garbage that causes adjacent and/or harmonic interference. I would warn that every Baofeng I have put on the ‘scope is crap on 2m, so much so I NEVER use them on 2m, and am not buying Baofeng unless it passes harmonic & spurious emissions testing on all bands that require those tests. After 3 years of testing every Baofeng multiband HT I put on my scope fails on 2m, so I ONLY ever use them on 440. I try to sell what I have, no one wants them.
Well, I’ve seen lots of hate for the Baofengs and I do own a few, so I checked and then had a friend check (we are both measurement nuts so we own plenty of RF test gear between us), all I can say is that his and mine would be legal if we were subject to the FCC regulations (fortunately we don’t live in the land of the free so aren’t subject to their regulations)
If they’d be FCC legal after I’d stuck a ~9dB gain block on them, I’m not sure, I don’t have the test results to hand to do the maths and don’t actually own a suitable amplifer so it would just have to be an exercise on a calculator but I am now curious.
I think the main problem, which I missed entirely and someone else pointed out, is that they’re not type approved for GMRS use so are defacto illegal to use on those channels with or without an amplifier.
Unless you are licensed… As he is…
Amen and hallelujah!
Any radio that can transmit on any frequency other than GMRS (or FRS) channels is illegal on GMRS. Please read the regulations. Licensed hams, however, can use any radio they like on any allowed ham frequency commensurate with their license class privileges, provided it meets the technical requirements. That is because hams have passed a test to access their knowledge of the regulations and their competency not to mess up.
RadioArtisan, are you k3ng? If so, i love your work! I use your keyer design all the time.
Unfortunately, given he’s in the U.S., the mere fact that the repeater can operate on either ham bands or GMRS bands means it’s definitely not type-accepted for GMRS.
I’m fully aware of the jurisdiction it was being used in. I was pointing out a jurisdiction where it wouldn’t be tolerated.
They specifically mentioned “UHF CB”: the Citizen’s Band Radio Service class license, either on the 27MHz “HF” band, or the 477MHz “UHF” band, does not permit this.
This is what I was pointing out. Thank-you for assuming that US laws are global.
The UV5 is not FCC type accepted for GMRS, so illegal at any speed in the US.
Btech sells a very good 50 W GMRS repeater for about $2000. It is FCC type accepted, fully programmable, and runs on 120 V or 12V. It contains everything you need except an antenna and feedline. It even has a clever built-in diplexer that works for all of the GMRS repeater channels.
Stop thinking for a while. You think too much before writing.
When I bought a Yaesu FT3D, I started scanning the UHF CB channels. The only channel I’ve EVER heard in use was #40 (originally designated “emergency”). Maybe it’s an Australian thing.
So if you stick to the other 39 channels, chances are the only people hearing you are the ones deliberately NOT on channel 40.
Channel 40 is often used by the trucking community, and is useful for little more than learning new ways to insult people verbally. Channels 5 and 35 are the official emergency-use channels… with 35 being specifically reserved as an “uplink” frequency for repeaters operating on channel 5.
https://www.legislation.gov.au/F2015L00876/asmade/text section 6(a)(ii).
Do you need a license to run a ham radio these days?
You need a license to transmit on one legally.
You bet, you need a license. A technician class license is not hard to get. It confers full VHF and UHF privileges. There are many more ham repeaters than GMRS repeaters, you likely wouldn’t need your own.
Using a NASTY transmitter is what ” ruin other peoples lives”
If you had ever looked at the output of one of these radios on a SA you would understand.
(I have, 5 or 6 of them. And the ARRL ALOT more. 95% are junk)
What harm will it do? I’m always interested in hearing about the harms that happen as they’re the only argument against letting hams operate on whatever frequency with whatever power
The older Baofengs were noisy, meaning they produced a lot of undesirable harmonics. These harmonics are radio signals on lower or higher frequencies than the original frequency, often completely out of the licensed band, and they can cause interference with other licensed radio operators. A radio emitting such noise is out of spec and besides being illegal, operating it is just unneighborly.
However that was years ago. Baofeng has vastly improved their radios, and any recently produced radio of theirs now meets spec and controls that noise. Running a side-by-side comparison in a spectrum analyzer shows a huge improvement in noise reduction.
But that doesn’t stop a certain set of old guys from continuing to bemoan Baofeng. (Especially people who spent $1500 on a Motorola instead of $40 on a cheap Chinese radio.) I’ve found that those kinds of people mostly just love to have something to complain about.
“ruins”
ROGER that! And amen!
The project looks nice, reminds me of a friend’s APRS box I have sitting in the garage.
The licensing fee for GMRS is unreasonably high in the US….
FRS has power limitations that prohibit the use of a power amplifier….
And finally….
Simplex repeaters…… HaHaHa
Just get your ham license and get it over with.
The ham bands are the best place to run your projects.
With this said; does HAD support “bootleg radio communications”? Enqueuing minds want to know. Considering that we have been living with “Time of arrival” direction finding since 1989 I would like to think that smarter minds would think twice about illegal operating a radio transmitter….
GMRS licensing is unreasonably high? Are you aware that is was changed to $35 for 10 years? That’s 30¢ a month.
I do agree that running a simplex repeater on GMRS isn’t great, but really, I’m not sure running a simplex repeater on the ham bands makes much sense either.
I myself have a 10W full duplex Motorola repeater with cheap duplexer, haven’t even really set it up since there are higher power functional GMRS repeaters in my area, and enough of them to need to coordinate.
This seems more like a wishful thinking SHTF solution.
FYI: It is not legal in the USA to use non-GMRS licensed radios to transmit on GMRS.
+1
As a matter of fact it is not legal to use a radio that is not type accepted for the service it is used on…
With one exception Amateur radio, you can use anything you can get to work on the ham bands…
Not the other way around.
Actually it is, FCC part 95 radios
Sadly, using a simplex repeater, under regular circumstances, on GMRS is not lawful in the US. Unless something has changed recently.
I might be missing it, but where in part 95 subpart e does it say a simplex repeater is not permitted?
https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E
It’s in the wording- in that repeater-specified frequencies are listed as ‘to be used only when transmitting to a repeater,’ it’s implied that therefore one should not use simplex on those channels. “ Only mobile, hand-held portable, control and fixed stations may transmit on these [n] channels. Mobile, hand-held portable and control stations may transmit on these channels only when communicating through a repeater station or making brief test transmissions in accordance with §95.319(c).”
Also, this article is incorrect to state that the GMRS repeater depicted is “ham adjacent,” GMRS, while not strictly an amateur radio service, still most certainly qualifies as a ham activity.
t. Licensed GMRS repeater operator
Surely nothing in that wording insists on the repeater being duplex?
You are correct, I was conflating with MURS and FRS. My apologies – everyone ignore my post.
Seems like it is easier (and cheaper) to get a HAM license than broadcast illegally on GMRS (Yes I am aware you can get a ‘family’ GMRS license, IE anyone in your family over 18 has a single GMRS license and the family can communicate).
However, as others point out, this is not GMRS type certified, and you shouldn’t be repeating on GMRS anyway.
But hey, neat to know I can get a 40w booster for my UV-5R knockoffs. For emergency use or if I ever get a HAM license.
Simplex Repeaters is not new, but its great to see this being revived and or revisited.
73’s de VE3HGO
Wow.. US citizen here, Licensed Amateur Operator as well, just dropped by the comments to say you guys will argue over anything. Also, an observation: Some of you are boot licking Govern me harder daddy types.
Gross, stop making electronics engineers cringe….
Is there any way to look at serial numbers or some other marking on the radio to confirm that it does not have a dirty transmitter? I bought a pair of these when my wife and I were shopping at Costco or Denio’s. I don’t want my Ham ticket to get swept up in some GMRS beef. Been licensed since 1978. Cheers!
Ah. Well I’d buy that for a dollar. Up to 50w with 5 Rm. GOOD NIGHT. AND SPEED OF LIGHT.