Re: Low Frequency Modulation of Side Tone.

Posted by Don Wilhelm-3 on
URL: http://elecraft.85.s1.nabble.com/Low-Frequency-Modulation-of-Side-Tone-tp373879p373881.html

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
>


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