[arm-allstar] hum on my allstar nodes

Sun Apr 26 22:42:33 EDT 2020

Unfortunately Yaesu mics are not usable because they have no internal DTMF
generator but rather a 4x5 XY resistance matrix. We used an Arduino to read
the XY voltages and produce DTMF in the radioless node.

The Kenwood/Alinco mics use 8V which is the standard output voltage on the
mic jack of their radios. This is reduced to 5V in the mic with a
regulator. You need at least 1.5 to 2 volts above that to regulate.
Something like this -

https://www.amazon.com/dp/B07RZT7J61/ref=sspa_dk_detail_3

*73 Doug, WA3DSP*
*http://wa3dsp.org <http://wa3dsp.org>*

On Sun, Apr 26, 2020 at 6:34 PM "Michael Fleetwood via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> 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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> > > > > >>
> > > > > >> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
> > > > > >>
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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
> > > >http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> > > >
> > > >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
> > >
> >_______________________________________________
> >
> >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
>
> Mike Fleetwood
> Canberra Australia and Sidcup UK.
>
> Worldwide email address is:     mfleetwood at gmail.com
>
> _______________________________________________
>
> ARM-allstar mailing list
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>
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>