‘USA 1776’ DMR Talk Group

DMR-logoOne of the nice things of D-Star and DMR is the ability to talk all over the world without the need of an HF rig and a bunch of big antennas. While this largely reduces a radio to a simple Internet-driven communication tool – just like Skype or other VoIP apps – it’s definitely nice to use.

There are a few problems surrounding DMR, one of which is the lack of more than two time slots. For example, if hams are using the Dutch Hytera network and occupying talk group 204 on slot 1, World Wide (which uses the same time slot) will be unavailable. Because 204-1 is a busy place, world wide QSOs are often impossible. It’s one of the reasons I thought of dumping DMR all together — I can talk to the same Dutch guys on analog while enjoying a much better quality audio.

There are reasons to keep DMR too. DMR is maturing; there are more than enough possibilities to put less pressure on the nation-wide network by going local. Now if only hams would do that…. but most don’t. Another reason to keep DMR for now is the gateway we recently added, which connects D-Star to our DMR network.

Not available on the Motorola network, sorry — some people responsible for that network appear to be so scared of such innovations that they will ban a repeater from the network if such a gateway is detected.

Talk group ‘USA 1776’ could add to the appeal of DMR. It’s unclear on which network this talk group will reside, but my best guess is that it will be the Motorola network.  MITCON writes:

The “USA 1776″ (English preferred) Talk Group will be distributed worldwide to DMR networks upon request.  The spirit of “1776” is to continue the Amateur Radio tradition of international friendship and to push the boundaries of technology in the new frontier of digital communications.

USA 1776USA 1776 is intended to be a flexible, politically neutral, unrestricted Talk Group that can be used as Push-To-Talk (PTT) or Full-Time (FT) to meet the operating requirements of a DMR Network.  DMR subscribers are welcome to use 1776 as a universal meeting place to “Rag Chew” or as a jumping off point and QSY to an alternative Talk Group if desired.  To add USA 1776 to your DMR Network please contact us to schedule a time for configuration & testing.


BFDX MT-7250 DMR Mobile

We knew BFDX already as a manufacturer of affordable DMR hand helds, and now a 30 Watt mobile radio popped up on the screen: the BFDX MT-7250. Grapevine Ham Radio sells this model for $329.99.

I find the number of channels/zones (160/50) a bit disappointing, but the price is right.


General Specifications
Frequency range VHF: 136-174MHz, or
UHF: 350-390 MHz, or
UHF: 400-470 MHz, or
UHF: 450-520 MHz
Channel Capacity 160
Zones 50
Channel Spacing 12.5KHz
Voltage DC 13.8V (±15%)
Frequency stability ±1.5ppm
Antenna impedance 50Ω
Dimensions 150(L)*160(W)*40(H)mm
Weight 1.29Kg
RF power output VHF/UHF high power:30W
VHF/UHF low power:15W
4FSK Modulation 12.5kHz (only data):7K60FXD
12.5kHz (data and voice):7K60FXE
FM Modulation 12.5 kHz:8K50F3E
Modulation Limiting +/- 2.5kHz @ 12.5kHz
FM Noise -40dB
Conducted  Emission -36 dBm≤1GHz/-30 dBm≥1GHz
Adjacent Channel Power ≤-60dB
Audio Response +1/-3 dB
Audio Distortion 3%
Digital Voice coder Type AMBE+2™
Digital sensitivity 5% BER:0.25 uV
Analog sensitivity 0.25 uV (12 dB SINAD)
Inter-modulation 60dB
Adjacent Channel Selectivity 60 dB
Spurious Response Rejection 70 dB
FM Noise -40dB
Audio Response +1/-3 dB
Audio output 3W
Audio Distortion 3% (typical)
Conducted Spurious Emission -57dBm
GPS Accuracy Horizontal Accuracy≤-10m
(with well signal)
TTFF (Time To First Fix) Cold Start < 1 minute(with well signal)
TTFF (Time To First Fix) Hot Start < 10second(with well signal)
Environmental Specifications
Working Temperature -20℃—+70℃
Storage Temperature -40℃—+80℃
Humidity MIL-STD-810C/D/E/F
Vibration & Shock MIL-STD-810C/D/E/F

Samhoo DMR

More and more Chinese manufacturers dive into the DMR market. This e-mail from Samhoo shows that there’s still room for more.

Greetings form Samhoo Sci & Tech Co.,LTD (Samhoo).

For the coming International Wireless Communications Expo (IWCE 2015), taking place March 18–19, 2015 in Las Vegas, USA, Samhoo wishes to invite you to visit our company booth NO. 2027. We look forward to welcoming you at the show. At the same time, we wish you will have a good trip in IWCE2015.

Attachments are the introductions and details of our DMR radio products. If you want to know more, please feel free to contact us and we will do our best to further our understanding. You can also find more information via our website: www.samhoo-pmr.com.

DMR—-  Samhoo is delighted to formally launch our DMR Portable SPH6000 serial, SPH2000 serial and DMR Mobile SPM6000 serial, which all fully compliant with ETSI DMR Tier 3 & Tier 2, and be available in UHF (350-400MHz, 400-470MHz) and VHF (136-174MHz) bands will release soon. 

TETRA—  Samhoo could provide fully integrated all feature industry TETRA module(smart size :86 X 43x 8) for Portable and Mobile devices, and be available in 806-870MHz,350-400MHz,380-430MHz,410-470MHz bands.

Samhoo is willing and open to work with all kinds’ partners, who could be distributor, dealer, ODM, OEM and technical cooperation etc, to explore Digital PMR radio business opportunity.

Best Regards

Alex YE
Oversea Sales Assistant
Samhoo Sci&Tech Co.,Ltd

Address: Room 601,Building 2th,Huaqiangyun Industrial Park,No.1-1,Meixiu Road,Meilin,Futian District,Shenzhen,China

Tel:+86-755-8316 0260 Fax:+86-755 8226 3733

What I find interesting about these Samhoo SPH6000 series is that ordinary TF cards are used for storage. This makes it possible to copy the configuration of one radio to another, just by transferring files. It would also be the few brands I know of who’s developing a VHF model.

Samhoo DMR ModelsFull specs can be found in this PDF document: Samhoo DMR SPH6000 Series DS-en

Also interesting (but probably very expensive and not really for hams) is their LK838 portable base station. When power goes down, this would still work — at least for a while.

Portable Ad hoc BS_samhoo-P1

Puxing PX-780 DMR Radio

Puxing jumped the bandwagon too and introduces the Puxing PX-780/PX-820 DMR Tier II radio. Prices unknown at this time; you have to mail them through Alibaba.com for more information.

PuxingThe radio is available in both VHF and UHF versions. GPS appears to be a standard feature.


General Specifications
Frequency Range 136-174MHz /400-470MHz /customized
Channel Capacity 1000/customized
antenna impedance 50Ω
Operating Voltage 7.4V  DC
Operating Temperature -30°C +60°C
store temperature -40°C +85°C
Battery Life in 5/5/90 operating mode
1700mAh standard Li-ion battery analog:10hours,digital:14hours
dust-protection and water resistant IP67
Size not including antenna 113.5mm×54mm×33.5mm
Weight with battery, antenna 270G
channel spacing 12.5khz
frequency stability +/-1ppm
Output Power low power:1W high power:4w
hum and noise -40dB@12.5khz
conducted,radiated spurious emission -36dBm@ <1Ghz,-30dBm@>1Ghz
adjacent channel power -60dB @12.5khz
ajacent transient channel power -50dB@ 12.5KHZ
FM modulation mode 12.5khz:11K0F3E
4FSK digital mode 12.5khz(data only):7K60FXD 12.5khz(data+voice):7K60FXE
modulation maximum deviation 2.5khz@12.5khz
nonactive slot power -57dBm
audio response +1dB–3dB
audio distortion 3%(type)
digital protocol ETSI TS 102 361-1,-2,-3
vocoder type AMBE+2TM
channel spacing 12.5khz
frequency stability +/-1ppm
analog sensitivity 0.35μV/-116dBm(20dB SINAD)0.22μV/-120dBm(type)
digital sensitivity 0.3μV/-117.4dBm(BER 5%)0.7μV/-110dBm(BER1%)
intermodulation TIA603C:70dB ETSI:65dB
Adjacent Channel Selectivity TIA603C:65dB@12.5khz ETSI:60dB@12.5khz
co-channel rejection 12dB@12.5KHZ
spurious response rejection TIA603C:75dB ETSI:70dB
conducted spurious emission -57dBm@<1GHz,-47dBm@>1GHz
blocking 84dB
rated audio power 1w
audio response +1dB–3dB
rated audio distortion 3%(type)