Using RF amplifiers with DMR and Openspot #dmr


 Hi Charles,

You need an UHF amplifier with has FAST diode switching from receive to transmit mode and visa versa.

Because every 30 milliseconds the the amplifier has to be switched OFF to let a receive signal come in for DMR synchronization.
The only DMR amplifier I have seen so far and bought was on e-Bay, but it cost about $120 Can.

Guenther VE2BHH

On 2017-01-24 02:57 PM, Charles Guérin wrote:

Hello everyone, I saw that there are amplifiers that are marked as 'DMR capable', as anyone used on of these recently ?

I understand a standard FM linear amplifier will not work properly with a MD-380 or similar transceiver, but I would like to see if I can give my Openspot a little more coverage (1 or 2 watts) using a RF amplifier that can be had for less than 20$. Any thoughts on this ?

I uploaded a file in the group's that discussed using amplifiers with DMR radios, which mentions that a DMR base station uses 4FSK (C4FM) modulation, as opposed to TDMA on a user's radio. Since the Openspot is working simplex would it be possible to make it work ?

Thanks / merci!

Charles VE2FXO

Mario - VE2TSM

Hi Charles,

I am looking at 2 solutions to increase my DMR signal from Rawdon to Montreal.
1st is a small UHF Beam, pretty cheap as a solution, and the other is a
Mirage VHF / UHF Amp  BD-35 ($ 209 U.S.) that is said to be D*Star ready
i would think it would also be fast enough for DMR, details found in the MFJ catalog

you may want to give MFJ A call, to make sure it switches fast enough for DMR

it puts out 35w on UHF

I hope this helps
73's MarioT  VE2TSM