[arm-allstar] hum on my allstar nodes

Sun Apr 26 18:26:34 EDT 2020

I do have a Yaesu MH-48 which I have not yet tried, mainly because I 
thought the Alinco was supposed to run at 5v which would be convenient.

What voltage would be optimal to feed to the Alinco, and the Yaesu 
mics and I can see about producing that.

Many thanks for your kind advice.

Mike
VK2AMF.

At 08:15 AM 27/04/2020, you wrote:
>I can almost say with certainty that this is caused by EMI from the FOB
>and/or PI getting into the microphone. The mic has a 5V regulator and when
>you run it on 5V (vs the usual 8V on a Kenwood radio) the regulator does
>not regulate and instead passes all the 5V bus garbage to the high gain mic
>amp. This is very hard to get rid of with filtering. What has been done by
>some is use a 5V to 8V boost supply (they are very small) to boost the 5V
>back up to 8V for the mic. Then the regulator in the mic will function and
>it will eliminate the noise. I have heard them and they are very clean.
>This is also why we did not use Kenwood or Alinco mics on the the
>Technobygeorge radioless nodes but rather the Yaesu mics.
>
>*73 Doug, WA3DSP*
>*http://wa3dsp.org <http://wa3dsp.org>*
>
>On Sun, Apr 26, 2020 at 6:02 PM "Michael Fleetwood via ARM-allstar" <
>arm-allstar at hamvoip.org> wrote:
>
> > I am having a problem with a background hash others hear when I
> > transmit using a radioless node with a Pi3A+ an Alinco EMS57 mic,
> > modified sound fob and audio amp. Received audio is perfect, but when
> > I listen to myself on the parrot the noise sounds a bit like an FM
> > signal that is not fully quieting. I have tried optimising grounding
> > and using different power supplies including a 12v battery and 7805
> > regulator, but the problem persists.
> >
> > Mike
> > VK2AMF
> >
> >
> > At 05:23 AM 27/04/2020, you wrote:
> > >The "RF" hum is caused by some odd phasing relationship and/or RF overload
> > >at the site. When you think of it you rarely transmit RF that close to the
> > >destination most of the time. We have found that distance and selecting
> > >locations that are best are about the only thing you can do in this case.
> > >It usually only happens when you are very close to the node. If this is
> > >your problem the only thing you can do is change locations of equipment or
> > >antennas and distance from your node.
> > >
> > >*73 Doug, WA3DSP*
> > >*http://wa3dsp.org <http://wa3dsp.org>*
> > >
> > >On Sun, Apr 26, 2020 at 11:57 AM "Chris Smart via ARM-allstar" <
> > >arm-allstar at hamvoip.org> wrote:
> > >
> > > > Thanks Doug.
> > > >
> > > >
> > > > What is typically the source of this hum? Wall-wart type power
> > supplies?
> > > >
> > > > 73
> > > >
> > > >
> > > > Chris
> > > >
> > > >
> > > >
> > > > On 4/26/2020 10:46 AM, "Doug Crompton via ARM-allstar" wrote:
> > > > > Hum on local RF nodes is a common problem when transmitting TO your
> > node.
> > > > > It is usually because you are too close to your node. If the hum
> > stops
> > > > when
> > > > > you move to another location, sometimes just a foot or two one way
> > or the
> > > > > other then that is probably the problem. It happens more often when
> > using
> > > > > antennas that are mounted on the node itself. One way to get rid of
> > it is
> > > > > to use those small mag mount antennas that have 10-15 feet of coax
> > and
> > > > get
> > > > > it away from your operating position or use an outdoor antenna. Other
> > > > than
> > > > > that there is no filtering or other way to eliminate it. If the hum
> > is
> > > > > constant at any location even walking hundreds of feet away then it
> > is
> > > > not
> > > > > this phenomenon.
> > > > >
> > > > > *73 Doug, WA3DSP*
> > > > > *http://wa3dsp.org <http://wa3dsp.org>*
> > > > >
> > > > >
> > > > >
> > > > > On Sun, Apr 26, 2020 at 4:08 AM "Jed Barton via ARM-allstar" <
> > > > > arm-allstar at hamvoip.org> wrote:
> > > > >
> > > > >> Hey guys,
> > > > >>
> > > > >> So i'm sure i'm not the only 1 with this problem. I've got all my
> > > > >> allstar pies plugged in.  They each have their own power supply.
> > It's
> > > > >> the typical wall wart.  They all produce a nice little hum that's
> > just
> > > > >> annoying.
> > > > >> I'm sure a lot of you guys have delt with this.  You hear it on the
> > > > >> node transmitter such as the Shari.  Any ideas for getting rid of
> > it,
> > > > >> or reducing it?
> > > > >>
> > > > >> Cheers,
> > > > >>
> > > > >> Jed
> > > > >> _______________________________________________
> > > > >>
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> > > > >>
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> > > > >>
> > > > > _______________________________________________
> > > > >
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> > > > >
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> > > > _______________________________________________
> > > >
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> > > >
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> > > >
> > >_______________________________________________
> > >
> > >ARM-allstar mailing list
> > >ARM-allstar at hamvoip.org
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> > >
> > >Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> >
> > Mike Fleetwood
> > Canberra Australia and Sidcup UK.
> >
> > Worldwide email address is:     mfleetwood at gmail.com
> >
> > _______________________________________________
> >
> > ARM-allstar mailing list
> > ARM-allstar at hamvoip.org
> > http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >
> > Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> >
>_______________________________________________
>
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Mike Fleetwood
Canberra Australia and Sidcup UK.

Worldwide email address is:     mfleetwood at gmail.com 