[Elecraft] k3 50Hz background noise

[Igor Sokolov]

The problem is solved. I thought I have to share  with others what worked
best or us. This solution came from Gary N7IR.

Try a few sheets of thin low carbon steel (in US called mild steel)
insulated from each other by sheets of printer paper.  Put this sandwich in
between and parallel to the K3 and the rotator controller.  That should
knock it down by many 10's of dB if it is magnetic coupling.  Make sure that
the sheets are as long as the case of K3 and twice as tall.  Also make sure
the sheets don't touch either case.  I've used this technique many times in
my professional life and it works every time.

Thank you Gary and thanks to all for alternative suggestions

73, Igor UA9CDC

>
> > My friend, K3 user is getting ready for CQWW SSB. In his
> > installation the
> > rotator control box that has pretty large transformer
> > inside.  The box is
> > only few inches away from one of the two K3s  and cannot
> > be moved. He has
> > discovered that magnetic field created by this transformer
> > interacts with
> > the AF transformer (Line in) in K3. The indused 50Hz noise
> > is only 20db down
> > from the audio signal. The noise is gone when line in is
> > switched off in the
> > menu but that leaves him without voice keyer which is
> > tough to be deprived
> > of in 48 hours SSB contest. Has anybody found a solution
> > yet. He now thinks
> > of taking the transformers out of the radio an bypassing
> > them. He thinks
> > that the problem roots to the fact that the K3 cabinet is
> > made of aluminum.
> >
> > 73, Igor UA9CDC