[Elecraft] Low Frequency Modulation of Side Tone.

[W3FPR - Don Wilhelm]

Jeff and all,

For a source of decent audio transformers for low power applications like 
that, look at defunct computer modem cards.  I have salvaged transformers 
from them for computer to audio equipment isolation for some time now - 
small and quite inexpensive (i.e. 'cheap', 'free', etc.)  Of course the more 
sophistocated way of handling such problems is with optoisolators, but they 
are not usually free, and they require a voltage source - transformers 
require no voltage.

73,
Don W3FPR

----- Original Message ----- 

> Problem found. I added a fixed audio out port to the K2. Disconnecting the
> wire to the sound card stopped the modulation.  An audio transformer in 
> line
> also eliminated the problem.
>
> Jeff Burns
> AD9T
>