[arm-allstar] 1KHZ whine

[Doug Crompton]

Just to carry my original comments about switching or digital noise a
little further there was just an incident with a user who had an audio note
on his signal that would slowly go from a keyup note of about 2khz down in
frequency to out of the audio range over a period of about 30-60 seconds.
It turned out he was using two of the small board switching modules, one to
power the Pi and one to power the radio. The switching frequencies which
are not crystal controlled were mixing and the difference was in the audio
range. Simply changing out one of the supplies to another manufacturer
solved the problem. So you can see that although we have vastly more
efficient supplies today there are many other problems we have to deal with.


*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*


On Wed, Apr 25, 2018 at 5:52 PM, "John Griffith via arm-allstar" <
arm-allstar at hamvoip.org> wrote:

> Hey everyone, I've never been able to completely get rid of an annoying
> 1KHz saw or square wave whine on transmit and or receive. Gotten close to
> where you really have to turn the volume up way high to hear it, but mostly
> noticeable ant normal levels. I hear it on other stations during their
> transmissions, and I ask them if they're running DMK URI's, and they all
> say yes.
> Has anyone else noticed this, and or has anyone dug for the source of it?
> I suspect URI, as this seems to be a common denominator.
>
> John N7OKN
>
>