Strange hotspot behavior

MMDVM_HS Hat hardware
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W2SJW
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Strange hotspot behavior

Post by W2SJW »

Guys,

I'm still in the breaking-in stage of my new MMDVM_HS + Pi-0 setup, and I'm having a strange issue with the unit on DMR.

When I engage in a QSO, the longer it goes on, the more the hotspot will stop passing signal that my 7550e is able to decode. If the other station approaches 120 seconds or so, my HT will stop decoding the transmission (even though the MMDVM is still TX'ing & I can see signal on the HT's screen).

Any idea what to start looking at to cure this?
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MW0MWZ
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Re: Strange hotspot behavior

Post by MW0MWZ »

You might want to try moving the TXOffset around a little, my guess is that as the board heats up, the frequency is shifting.
Try steps of 50 at a time, start at -200 and work up to +200 and see if its any better/worse at each.
Andy

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W2SJW
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Re: Strange hotspot behavior

Post by W2SJW »

Amazingly, it's been stable all day now. I took apart the upper-half of the case & re-seated the MMDVM, made some more tweaks to the dashboard, and (most importantly) hooked it up to its own 2.0A power supply.

It seems to not be doing it anymore. And, it's been giving me between 0.2 - 0.5 BER with the offsets set at 0...
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K9JTV
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Re: Strange hotspot behavior

Post by K9JTV »

MW0MWZ wrote: Sun May 27, 2018 10:37 pm You might want to try moving the TXOffset around a little, my guess is that as the board heats up, the frequency is shifting.
Try steps of 50 at a time, start at -200 and work up to +200 and see if its any better/worse at each.
I picked up one of these little 5v fans and mounted it where it blows across both my raspberry-pi zero w and jumbospot board. Got it HERE from ADAFRUIT.COM. Dropped the pi cpu temp by about 20° F.

-Jeff
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KE0FHS
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Re: Strange hotspot behavior

Post by KE0FHS »

I picked up one of these little 5v fans
Where did you plug in the fan?
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n9mxq
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Re: Strange hotspot behavior

Post by n9mxq »

Pin2 for +5v and pin3 for ground.
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K9JTV
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Re: Strange hotspot behavior

Post by K9JTV »

KE0FHS wrote: Mon May 28, 2018 2:08 pm
I picked up one of these little 5v fans
Where did you plug in the fan?
My Nextion came with a little board that is USB on one end and +5v/Ground on the other. I used that board to power the fan.

-Jeff, K9JTV
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KE0FHS
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Re: Strange hotspot behavior

Post by KE0FHS »

My Nextion came with a little board that is USB on one end and +5v/Ground on the other. I used that board to power the fan.
Oh, good idea. Thanks!
73, Toshen, KE0FHS
Playing with Pi-Star (unofficial notes about setting up and using Pi-Star):
https://amateurradionotes.com/pi-star.htm
n9mxq
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Re: Strange hotspot behavior

Post by n9mxq »

KD9JTV wrote: Mon May 28, 2018 3:31 pm
KE0FHS wrote: Mon May 28, 2018 2:08 pm
I picked up one of these little 5v fans
Where did you plug in the fan?
My Nextion came with a little board that is USB on one end and +5v/Ground on the other. I used that board to power the fan.

-Jeff, K9JTV
I like this idea better also ;-)
Gene in Belvidere IL
Please don't email me with questions.
That's what these forums are for.
There's much more brainpower collected here
than I have alone.
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