[Elecraft] K3S Audio buzz on transmit, especially AM

[Nicklas Johnson]

I did in fact wonder the same thing myself-- whether the solar controller
could be injecting some noise or just making some noise, so when I did the
battery test, I disconnected the battery from the controller and ran
directly from the battery to the rig.

I couldn't tell you a dB level of the buzz without having some more
accurate equipment to measure it, but it's very noticeable relative to my
voice when testing.  It was enough to make me think I had either RF
feedback or a ground loop giving me grief.

There could be something to be learned from the predominant frequencies
present in the buzz... they're more or less 120Hz apart, but they start at
a weird place-- 350 isn't a multiple of 60 or 120, but that particular spur
and the 470 and 830 Hz spurs are all pretty exact, though of course it's
not impossible that there's some FFT error in determining those frequencies
and they're actually 360, 480, and 840.

Curious, though, is that running on a battery, there's nothing to inject a
60Hz or 120Hz noise directly, especially not once I disconnected the rig
ground from the ground rod outside.  Which makes me wonder if the buzz is
just something in the house that's mixing with the carrier and
re-radiating.  For my next trick, this weekend I think I'll take everything
outside on a picnic table, away from house wiring, etc., and see if that
changes anything, or I might start with just the receiver outdoors and away
from house wiring, and then move on to both if needed.

   Nick

On Fri, 26 Apr 2019 at 14:37, K8TE <billamader at gmail.com> wrote:

> The word that struck my attention is "solar" and the possibility of that
> controller causing noise.  When you were connected to just the battery and
> dummy load, was the battery disconnected from the solar system?  And, at
> what level was the buzz relative to a full power carrier?
>
> Every transmitter has some noise on its signal.  Specifications and FCC
> rules in some cases call for a specific ratio.  I can't imagine a factory
> reset solving a problem like this.  Be certain you have saved your
> configuration first.  Solving issues like this is not magic, but sometimes
> a
> mystery.
>
> 73, Bill, K8TE
>
-- 
*N6OL*
Saying something doesn't make it true.  Belief in something doesn't make it
real. And if you have to lie to support a position, that position is not
worth supporting.