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Friday, 30 December 2016

DMR radios to avoid!

There has been a new trend lately of the Chinese radio manufacturers making DMR radios that don't do TDMA. TDMA is the pulsing the radio does that actually makes it transmit only half the time on the channel, allowing another user to transmit in the other half. This is what allows DMR repeaters to repeat two conversations at once. TDMA is a fundamental part of the DMR standard.

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

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.


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)

8 comments:

  1. Replies
    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.

      Delete
  2. It is very good to know what radios to avoid. I am about to get a radio for Fusion and one for DMR.
    I would have hated to buy something sold as DMR that didn't work. Thanks 73
    Bill AB9QU

    ReplyDelete
  3. Dpmr is a different digital mode it is not dmr please do your homework

    ReplyDelete
  4. Dpmr is a different digital mode it is not dmr please do your homework

    ReplyDelete
  5. Just 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?

    ReplyDelete
    Replies
    1. Could be, but I doubt they would release a new version so soon after the original

      Delete
  6. Hello, I can not program the Baofeng DMR to listen to the frequencies.
    I 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

    ReplyDelete

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