These new "DMR" radios that have only come about recently are unable to do TDMA. They are being sold in many cases as tier 2 DMR radios, which means they should be able to do TDMA to use repeaters properly, but they cannot. (See my video for an explanation of the difference between the tiers).
What is the consequence of this?
Well, the radios that claim to be tier 2 DMR radios actually should work on DMR repeaters, but they will transmit in the timeslot you want to use AND the timeslot you're not using. This means that nobody can use the other timeslot while you're using the repeater with one of these terrible radios. It's basically jamming the repeater! This will probably get you banned from using the repeater.Why are the manufacturers doing this?
Hardware capable of doing TDMA is more expensive. That is the simple reason. The manufacturers are trying so hard to get the cost down and get people to buy their product instead of someone else's, that they are missing out essential parts of the radio. Show them that this is not right by spreading the word and refusing to buy these radios.The list
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| Baofeng DM-5R |
1. Baofeng DM-5R.
The original version of this radio. Sold as Tier 1 only (although technically this is incorrect as tier 1 is for license free PMR446 band only). This radio will work on simplex channels fine with other DM-5Rs, but not with other DMR radios before it is updated. Once it has been updated (to change the vocoder from the cheap ASELP vocoder to the DMR standard AMBE2+), it should work with any other DMR radios on simplex channels only.
2. Baofeng DM-5R plus.
Sold as a tier 2 radio. This radio should work out of the box (i.e. without any software upgrades) with other DMR radios on simplex channels. It will also work on repeaters, but it will jam the other repeater slot so you should never use this radio on a DMR repeater. This is a hardware limitation of this radio, so don't expect there to ever be an update that will allow it to work properly on repeaters.
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| TYT MD-398 |
3. Radioddity GD-55/TYT MD-398
The Radioddity GD-55 is a re-branded TYT MD-398. Neither of these radios can do TDMA. This is a hardware limitation so no firmware updates or upgrades will be able to change this. This means that the radio could potentially work on DMR repeaters but it will jam the other timeslot like the DM-5R plus, so should never be used on a DMR repeater.
Note: The GD-55 Plus does work fine on both timeslots according to information I've seen online, but beware that this radio is NOT dual band, unlike the GD-55.
4. TYT MD-680
A 10W radio with no screen.
That's all for now. If you know of any other radios with this problem, please leave a comment so I can add it to the list. I'll try to keep this list up to date.
Please share this post to spread the word and stop others from being tricked into buying these radios.
If you enjoyed this article or found it useful, you might like to watch some of my videos on my YouTube channel.
If you're looking to buy a DMR radio then I currently recommend these radios:
TYT MD-380. (Link redirects to most appropriate site for your country)
TYT MD-390. (Waterproof version) (Link redirects to most appropriate site for your country)
Retevis RT-2.
ReplyDeleteIs a Tier 1
Thanks for the comment. I just looked up that radio and it is a dPMR radio, not DMR. This blog post/article is only about DMR radios. Thanks for the suggestion anyway though.
DeleteIt is very good to know what radios to avoid. I am about to get a radio for Fusion and one for DMR.
ReplyDeleteI would have hated to buy something sold as DMR that didn't work. Thanks 73
Bill AB9QU
Dpmr is a different digital mode it is not dmr please do your homework
ReplyDeleteWhat an unhelpful comment !
DeleteDpmr is a different digital mode it is not dmr please do your homework
ReplyDeleteJust for interest, I ordered a GD-55 - mainly for non-ham purposes where the slot problem wouldn't matter, but they told me that they all have a 'fault' and I have to wait for a new batch. Sounds unlikely, but maybe a mk2 is on the way?
ReplyDeleteCould be, but I doubt they would release a new version so soon after the original
DeleteHello, I can not program the Baofeng DMR to listen to the frequencies.
ReplyDeleteI put totas to the frequencies it receives the carrier (green led) but it does not have audio.
You have some video that shows step by step how to program.
Thank you
if possible send via E-mail (py2tod@yahoo.com.br)
73
I didn't see your pages and coverage of the DMR radios until I had already bought the Radioddity GD-77. After I turned talkabout to single wait instead of double wait, and programmed in scan lists, the radio has served me well so far on DMR repeaters, but I have forwarded your pages to a friend who is also getting into DMR. I have recommended to him the TYT MD-380 and MD-390. Any information you can give on Hytera radios? I'd really like to get into those, and am researching rolling out a single site DMR repeater set up on commercial bands for a convention that I volunteer at. I'm currently looking at Hytera radios, the TYT MD-380 and 390 for these setups.
ReplyDeleteThanks for everything and 73 de Alex K4RNT
The GD-77, unlike the earlier Radioddity rigs mentioned in the story, is a proper dual band and dual time slot radio. Its only major limitation is the small storage capacity for contacts. But it's the least expensive option on the market, so it's a good choice if you can live with the storage limits. It appears to be identical to the TYT MD-760, a model that is only sold in China; Radioditty has the rights to sell it elsewhere.
DeleteWhat is the cheapest dmr tier 2 radio in 2019? It can be without display.
ReplyDeleteI own a GD-77 is works but barely. I know folks love them because they are inexpensive (VERY) especially for a dual band radio. However, besides the small amount of memory for Channels, RX Groups and Contacts; there are 3 major flaws in the firmware. I have be badgering Radioddity to fix them for 2 years with no joy. The problems are:
ReplyDeleteThe 3 most important flaws in the the radio:
1 - The Admit Criteria does not work as it supposed too. Or actually it does not work at all
2 - The Talk Permit Tone does not work as it should and may be related to the Admit Criteria
3 - The need to use RX Groups and limited number effectively limits the radio to 128 Talk Groups which was reduced to 64 in more recent firmware. All radios I own and am aware of, do not require the use of RX Groups if you jut wish to hear the same TG and the TX Contact.
For those that solely use hotspots it is less of an issue, but on repeaters it is the cause of unintentional interference.
Before those that say it is a great radio and I don't know what the hell I am talking about, I have been using and installing MotoTrbo/DMR repeaters and systems before they were even considered for ham use. Additionally, I hold several Motorola certificates for similar modes.
Buyer beware! Spend a few extra bux for an Anytone DT-868 or 878 you will be glad you did.
73
Jon
Thank you for all the info on your website. I am a beginner in ham radio so your site fills a big void in me as I try to understand this great technology! My question: why aren't the major brands represented in hand helds such as, Yaesu,Kenwood, and icom??
ReplyDeleteThose brands don't make DMR radios suitable for amateur radio. In fact out of the three you mentioned I believe only kenwood makes DMR radios but they're aimed at the commercial market rather than amateurs. The programming software would probably be difficult to get hold of and radios would not have any programming direct from the keypad.
DeleteWhat about the Baofeng DM-1702?
ReplyDelete