TX output

MMDVM_HS Hat hardware
Post Reply
Posts: 14
Joined: Mon Oct 12, 2020 8:36 pm

TX output

Post by 2E0WHN »

I have read that the MMDVM Pi output is 10mW at 100% output. I do not know if this is true.

What I am thinking of doing is attaching different antennas to the Pi and seeing if range can be a factor in using my Anytone H/T while walking about my area. Antennas like the Diamond SRH805S antenna, along with the Sharman flexible antenna and a 70cms ground plane antenna. Want to see if range can play a part in squeezing out more afar contacts as I live in SW Scotland on the Southern Upland Way walk. This a hill area (141m ASL) so would like to see if I can cover my area mostly with the MMDVM and some antenna to have when out and about without using a X30 antenna.

So is the 10mW an actual power output or is is it more? Also do you think I could cover my area with the Pi hat with just a ground plane antenna or the others described?
DMR ID: 2347152

As a child I was made to walk the plank.
We couldn't afford a dog.
Pi-Star Team
Posts: 1257
Joined: Thu Apr 05, 2018 5:30 am

Re: TX output

Post by M1DNS »

Remember in UK hotspots are permissable without the need for additional licensing as they are intended to cover your property (station) if you are looking to cover a wider area, you might need application for a NOV.

I'd double check the regs if your thinking of having it cover a wider locale.

Sent via smoke signals from my SM-G935F M1DNS (Admin)

Andrew M1DNS.
Pi-star Admin Team.
Posts: 2
Joined: Sat Jan 14, 2023 10:51 am
Location: DE, Cologne

Re: TX output

Post by DF1KZ »

According to the datasheet the maximum output-power of an ADF7021 (mostly used in hotspots) is 13dBm.
Looking at the signal of this device, I would not recommend to connect it to an outdoor antenna or an power-amplifier without additional filtering means.

Wolfgang, DF1KZ
Posts: 79
Joined: Tue Apr 24, 2018 5:34 pm

Re: TX output

Post by G4AON »

I have three “hotspots”, two are MMDVM boards and the other is a 2m DVAP dongle.

They all produce between 10 and 12mW output, as measured with a Rigol spectrum analyser and attenuator. This is the specification of the IC used in the boards.

The maximum range I can “ping” one of the 70 cm MMDVM units is between 200 and 300 metres across a housing estate. The terrain is flat with few houses. The hotspot is located indoors near a large window favouring the direction of the test, it is around 1.5 metres above outside ground level and the handheld is an Icom ID51 plus 2, which gives a measured 80mW (SLO power setting). The hotspot has a 70mm long helical mounted on the SMA socket and the handheld uses the stock antenna (FA-S270C).

I think that range is pretty impressive and more than enough to cover a typical house and all but the largest garden, even without resorting to an outside antenna, or mounting the hotspot on an upper floor.

73 Dave
ID51E plus 2
AnyTone AT-D878UV
Chinese MMDVM on a Pi Zero W
DVAP on a Pi 3B
Post Reply