[TenTec] Headphone/speaker distribution

[Ken Brown]

> So far I have not seen anyone offer a circuit for an audio breakout box which will have an audio amp(s), volume control(s), and jacks for 2 or more headsets with their microphone circuits...  This would be really handy for lots of rigs, and for visitors to the shack to be able to don a headset and listen or operate also.. Also, very handy for a teaching situation where new ops are being introduced to contesting...
>   
There are many applications for something like this. For contesting it 
can allow spectators or "off duty" operators to follow the action.

I built something to do this that uses only variable resistors, fixed 
resistors and stereo headphone jacks. It plugs into the external speaker 
output of the rig, so there is plenty of audio available to compensate 
for the attenuation through all the resistors. The speaker out put of 
this box uses a wirewound "rear speaker fader" from Calrad. The 
headphone jacks use 100 ohm carbon film pots from mouser. All outputs 
are isolated with fixed resistors, so that a direct short at any output 
(such as a mono phone jack which shorts one output of a stereo jack) 
does not kill the audio coming out of the others. No active components, 
No power supply. Works great.

DE N6KB