My Yaesu handheld will often buzz when receiving the local repeater
when the charger is plugged into the side of the radio. I know what
you are thinking-- those cheap wall chargers are not filtered very
well, that's why I'm hearing buzz. That may be true, but the buzz I
am hearing is not from skimpy filtering of the DC feeding the radio.
I believe it is caused by the rectifier diodes in the charger, which
will cause a form of intermod to be produced, which basically
modulates RF at a 60 or 120 cycle rate. The level of buzz will vary
greatly as I move around the radio, touch the radio, etc. Certain
positions will produce intolerable buzz, others none at all.
I know, the charger does not directly handle any RF. But it is
inevitably a part of your antenna system whether receive or transmit,
especially when using a duck on a radio. Therefore, RF on the wire to
the charger, and the AC side too, ends up in the rectifier diodes, and
is <modulated>. I've notices this phenomenon on other radios too, not
just my Yaesu, just as you have.
I think you are experiencing the same thing that I do here. I haven't
<benched> the theory presented here to prove it right or wrong, but it
might be useful to try some small RF bypass caps on each diode in your
power supply(s)... Or, ferrite chokes on the wire from the charger.
Laryn K8TVZ
>
> On Nov 21, 2005, at 5:43 PM, n60sb wrote:
>
> > I am using two Icom IC-2AT hand held radios as a low power "one way"
> > repeater system. This system provides a full quieting signal into a
> > local repeater whenever I use another HT around the house. The one
> > way transmitter uses a yagi antenna in the attic and the frequency is
> > set to a local repeater input frequency. The one way receiver uses a
> > simple rubber duck antenna (high sensitivity is not an issue here) and
> > listens to an offset frequency opposite that of the local repeater
> > thus allowing me to listen to the local repeater directly on my HT.
> > Everything works great with one exception. Whenever I stand in a few
> > specific locations around the house, an irritating buzz is transmitted
> > from the one way repeater.
> >
> > I did some additional testing and discovered that several other two
> > meter receivers (various brands) in my home will receive a buzzing
> > sound whenever I transmit from several specific locations within my
> > home using various brands of hand held radios. The exact location
> > where the HT produces the buzz varies with different receivers that
> > are located in different places in my home. Incidently, it makes no
> > difference if the output power of the HT is increased or decreased.
> >
> > This problem may be obvious to others, but my friends and I are unable
> > to figure it out. If I knew what was causing this buzz, I may be able
> > to resolve same. Any comments or help would be welcomed!
> >
> > 73!
> >
> >
> >
> >
> >
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> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
>
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