[Elecraft] Re: ghost signals

[jhaynes@alumni.uark.edu]

I'm a little behind on my reading, bu so far I haven't seen anybody 
mention the following.  I have had the experience with a couple of
Kenwood TS-430/440 rigs where a spurious frequency appeared in the
output as the RF power was increased.  This was when using audio FSK,
and as I recall the spurious tone was not being shifted, so it was 
perhaps something different from what we are talking about here.

In one case we were able to get rid of the spurious tone by plugging the
TS-440 power supply into a different circuit from the one feeding the
computer and TNC.  In the other case I got rid of it by using an
isolation transformer between the TNC and the mike jack.  Both of these
installations involved using a PK-232 rather than a computer and sound
card.

One thing about Kenwoods, and I don't know about other radios, is that
they have a separate ground wire for the mike element in the mike
connector, separate from the ground wire used for PTT and shield.
That's why I decided to try an isolation transformer.

I can't explain it (and I've been doing RTTY for 45 years, hi) but
that has been my observation.  So when I build sound-card-to-radio
hookups these days I always include an isolation transformer.  (Since
two of my radios are Kenwoods, and I figured it wouldn't hurt when
used with the Elecraft as well).

Jim W6JVE