[Elecraft] K3(s) Headphone Splitter

[Jim Brown]

On 4/25/2018 10:54 AM, Rich wrote:
> Is there a commercial item for this purpose?

Yes, the RANE HC-6 would work. And they make several other small mixers 
that make it easy to switch and route audio.  While the mixers may not 
have a stereo headphone output, you could easily make a cable adapter 
from the outputs to a cable-mounted stereo jack. I would study their 
catalog and look for the products used on ebay.

There's also a discontinued Shure product that does what you want. It's 
the model FP22 headphone amplifier. Runs on internal batteries or 12VDC. 
Very nice.

>
> I know I will need an audio isolation transformer between each radio 
> and the splitter/switch.   Any suggestions on what a good impedance 
> value would be for those transformers?

No, a transformer is NOT needed. All that is needed is proper bonding 
between all equipment in your station, including audio gear like the 
HC-6 or FP22.  Study
http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC