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Strange hotspot behavior
Posted: Sun May 27, 2018 5:58 pm
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?
Re: Strange hotspot behavior
Posted: Sun May 27, 2018 10:37 pm
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.
Re: Strange hotspot behavior
Posted: Sun May 27, 2018 11:25 pm
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...
Re: Strange hotspot behavior
Posted: Sun May 27, 2018 11:31 pm
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
Re: Strange hotspot behavior
Posted: Mon May 28, 2018 2:08 pm
by KE0FHS
I picked up one of these little 5v fans
Where did you plug in the fan?
Re: Strange hotspot behavior
Posted: Mon May 28, 2018 2:31 pm
by n9mxq
Pin2 for +5v and pin3 for ground.
Re: Strange hotspot behavior
Posted: Mon May 28, 2018 3:31 pm
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
Re: Strange hotspot behavior
Posted: Mon May 28, 2018 3:43 pm
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!
Re: Strange hotspot behavior
Posted: Mon May 28, 2018 3:45 pm
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
