[Elecraft] Multiple audio outputs for K2.

[jeff_elecraft@burnshome.org]

I would like to have multiple audio outputs for my K2 all hooked up at the
same time. One output for the computer, one for a speaker, and one for
headphones. Ideally each output would have independent volume control. At
least the headphone jack needs a low pass filter like the front panel
headphone jack on the K2.

At home I like to have the computer running CWGet. This makes it easy to
practice sending CW. Also, the spectrum display makes tuning a signal really
easy. At Field Day it is nice to be able to connect a speaker and headphones
at the same time. 

Currently I am using a Y-connector plugged into the rear panel audio jack.
This works ok to drive the computer and my communications headphones. Ear
buds have too much high frequency hiss if connected this way. Unfortunately,
to use the speaker I have to disconnect the computer. Using the audio out of
the computer to drive a speaker does not work because there is a time delay
in the audio. 

I have looked at the various fixed audio output modifications for driving
the computer, but none of them are completely satisfactory. EA3BLQ's digital
interface looks like the most elegant, but it does not output the side tone.
There is one reference in the archives list about mixing the side tone into
the fixed audio out, but requires an extra jumper between boards. I am also
concerned about the extra current drain from adding amplifiers into the K2
that cannot be turned off when they are not needed.  

It seems I need an external audio breakout box with at least three audio
outputs with individual volume controls.  To have enough drive for a speaker
it would need an amplifier. Provision is needed for using both stereo and
mono speakers. A simple low pass filter on the outputs is desirable. An
isolation transformer on the computer line would probably be a good idea.   

Does anyone know of a reasonably priced commercial product that would fit my
needs? Suggestions for an elegant home brew design would also be
appreciated.


Jeff Burns
AD9T