MMDVM With more power say 5 Watts

[KG7PBS]

Hey guys I was wanting to see if anyone has played with one to put out more then it’s .5 Watts. I would really like to have one put out 5 Watts so I can set it up a hilltop and get better range? Thanks

 

[Hit_Factor]

I think you'll need to be coordinated with the local Repeater Coordinator. Could be these guys NARCC - Northern Amateur Relay Council of California.

 

[bill4long]

You can easily make a "high power" hotspot from a GD-77. It will put out about 4 watts. You need OpenGD77 firmware to do it. The OpenGD77 site is currently not allowing download because of some licensing dispute, but if you go to the TGIF server, group 31665, Robert will get you a copy. Get on that group and call for Robert, and he'll know you're calling for him.

Personally, I have a hotspot using a Kenwood V71 and Scott Zimmerman's STM32_DVM controller. 45 watts on UHF, 50 watts on VHF. Using a Diamond X-300 up 30ft on a slight hill. About 20 mile range from my mobile.

Repeater Builder STM32-DVM

 

[KD8DVR]

A high power hotspot (except maybe the GD77 concept) is useless. You could amplify your typical mmdvm hotspot.... what then. It transmits farther, sure.... BUT *can it hear you*? I typical hotspot can transmit farther than it can receive... these radio on a chip devices are notoriously deaf. You transmit 3 miles.... and you have to be within 100 feet to hear you. Bad Idea.

 

[I_am_Alpha1]

I think you'll need to be coordinated with the local Repeater Coordinator. Could be these guys NARCC - Northern Amateur Relay Council of California.

"NEED"...coordination is optional, not mandatory. Yes, you are a dick if you don't and someone will try to quote other laws claiming not following good practice. Coordination is nearly impossible these days...and that shouldn't shut down someones legit project--as long as they are not causing harmful interference.

 

[I_am_Alpha1]

A high power hotspot (except maybe the GD77 concept) is useless. You could amplify your typical mmdvm hotspot.... what then. It transmits farther, sure.... BUT *can it hear you*? I typical hotspot can transmit farther than it can receive... these radio on a chip devices are notoriously deaf. You transmit 3 miles.... and you have to be within 100 feet to hear you. Bad Idea.

Plugging your hotspot into a PA is wrong...and that's not what one should consider a high power hotspot. Plugging your MMDVM into something like a Motorola CDM or Yaesu DR-1X would be a high power hotspot...and a legit project. There are lots of radios that can be connected to an MMDVM board to create a high power hotspot...Google away.

 

[KG7PBS]

A high power hotspot (except maybe the GD77 concept) is useless. You could amplify your typical mmdvm hotspot.... what then. It transmits farther, sure.... BUT *can it hear you*? I typical hotspot can transmit farther than it can receive... these radio on a chip devices are notoriously deaf. You transmit 3 miles.... and you have to be within 100 feet to hear you. Bad Idea.

Thanks guys I am going to go with the OpenGD77. It will be better for what I am looking to do. I live on Sacramento CA and we don’t have much on 440 because of the USAF. and only 2 VHF DMR box’s. I can use. I like the GD77 better.

 

[bill4long]

A high power hotspot (except maybe the GD77 concept) is useless. You could amplify your typical mmdvm hotspot.... what then. It transmits farther, sure.... BUT *can it hear you*? I typical hotspot can transmit farther than it can receive... these radio on a chip devices are notoriously deaf. You transmit 3 miles.... and you have to be within 100 feet to hear you. Bad Idea.

Assuming you're talking about the Chinese MMDVM boards, you are right. The receiver sensitivity on those things are quite bad. They do exactly what they're designed for- the work as a short range hotspot.

 

[kb9mwr]

I think you'll need to be coordinated with the local Repeater Coordinator. Could be these guys NARCC - Northern Amateur Relay Council of California.

There is very little or no filtering on the final output stage of the hotspots. They are pretty dirty. But at 10mW there is little cause for concern.

If you amplify the output from a Shark, or a DV-mega or anything similar you will be amplifying not only your tx frequency but all the other frequencies.

If you have that kind of money to throw around with a OpenSpot and amplifier, then buy a cheap RTL-SDR to use as a spectrum analyzer so you can understand how you are polluting the band.

SATSAGEN Spectrum Analyzer Software Updated: Now Supports RTL-SDR

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