[arm-allstar] Asterisk - Hum

[David McGough]

Hi Eric,

I battled ground loops in several cabinets early on in my AllStar days,
using URI adapters. I've got an assortment of repeaters, including Kenwood
TKR's and GE Mast II hardware, etc.  The always-fixes-hum-100% solution I
found is to add a new ground connection to the URI adapters. I now have
this retro-fit on every URI I've got deployed. Any new URI I purchase gets 
this mod before I sit it on the parts shelf.  See this thread for
photos, etc.:

http://lists.hamvoip.org/pipermail/arm-allstar/2017-October/006302.html

As for the RPi3, some wall-warts work great, others not. If you've got a 
unmodified USB Fob, try using that Fob plugged into amplified speakers 
(e.g.:: standard computer speakers).  If the buzz is still present, try 
another 5V power source for the RPi3.  If the buzz is gone, check out your 
fob to 888 wiring.


73, David KB4FXC





On Wed, 13 Dec 2017, Eric Smyder wrote:

> Thanks for answering my inquiry, David.
> 
> The Pi3 is powered by the supply that came with it.  Is that supply
> considered stable and clean enough?
> 
> The BF-888s is battery-powered.  The interface is the homebrew interface
> following the USB FOB Simple Modification right in the DB shell.
> https://hamvoip.org/hamradio/usb_fob_simple_modification/
> 
> The W3HZU repeater runs the DMK URI interface off the IBM PC in the video.
> 
> How would one begin to attack the problem if it is a ground loop?
> 
> thanks,
> 
> Eric
> N3FIX
> 
> 
> On Wed, Dec 13, 2017 at 10:27 PM, David McGough <kb4fxc at inttek.net> wrote:
> 
> >
> > Hi Eric,
> >
> > You don't mention what type of interfaces you're using--like URI's,
> > homebrew fobs, etc.???
> >
> > The noise heard on the HamVoIP system sounds like noise from a switching
> > power supply and/or ground loop in the audio path.
> >
> > How are you powering the RPi3??  And, similarly for the BF888??
> >
> >
> > 73, David KB4FXC
> >
> >
> > On Wed, 13 Dec 2017, "Eric Smyder via arm-allstar" wrote:
> >
> > > Hello all:
> > >
> > > I've been experimenting with HAMVOIP, on a Pi3 at the home QTH with a
> > > BF-888s as my radio.  It is a remarkably good system and easy to
> > > configure.  However, I'm having an issue.  It is actually the same issue
> > I
> > > noticed on the W3HZU 6 meter repeater.
> > >
> > > The video links below exemplifies the issue.  When transmitting directly
> > > from the repeater with the hand-mic the repeater sounds great.  When I
> > > trigger the AllStarLink from Asterisk, or when the node makes an
> > > announcement or identifies, there is a distinct tone or hum.  I get the
> > > same thing on my Pi 3 at the house if I key the transmitter and speak
> > into
> > > the BF-888s.  It seems to be coming through the computer or being picked
> > up
> > > somewhere in the connections to the URI.  I have taken measures to shield
> > > the wiring between the radio and the URI, but the hum is still there.
> > >
> > > At W3HZU 6m AllStarLink
> > > https://photos.app.goo.gl/OtJn3aK2ZRCd6cPs2
> > >
> > > At the home QTH using the Pi3, where the hum is more noticeable.
> > > https://photos.app.goo.gl/XsUC4on5t04LH6CS2
> > >
> > > Has anyone else noticed this and is there something I can do about it?
> > >
> > > Thanks,
> > >
> > > Eric
> > > N3FIX
> > > _______________________________________________
> > >
> > > arm-allstar mailing list
> > > arm-allstar at hamvoip.org
> > > http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> > >
> > > Visit the BBB and RPi2/3 web page - http://hamvoip.org
> > >
> >
> >
>