One advantage to a passive (no amplification) approach is you will not have
any problem with picking up RF!
Jeff WB0LRX
----- Original Message -----
From: "Ken Brown" <ken.d.brown@hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, January 16, 2008 11:24 AM
Subject: Re: [TenTec] Headphone/speaker distribution
>
>> 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
>
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