[Elecraft] k2 headphone jack

[Tom W8JI]

<<One of the things I plan on doing is getting a simple 4 
output headphone amp from ART ($65).
Plug one or 2 pairs of headphones in, and output another to 
my computer, and another to a real amplifier/speaker setup.

That way I never have to unplug the set to have an output to 
my computer for Data or voice.>>

I use the line output for my computer, including sound 
recording. That way radio audio level settings never affect 
digital mode decoding.

I use the rear panel speaker out for my headphones or 
speaker, and have a desk mounted switch that lets me use 
multiple headphones on any audio channel. Any desk anywhere 
can hear any radio any time no matter what or who is using 
the radio. In the contest barn 5 people can listen to the 
same channel, or all on different channels. Since the K3 
speaker audio out is low impedance, and I bridge in with at 
least 160 ohms of load impedance, audio level does not 
change no matter how many phones bridge in.

To get speaker output I have a fader control and a mono amp, 
a cheap MFJ616. The fader moves the 616 to either left or 
right line, since I do not have stereo speakers.

ALL of the line taps, and the lead to the computer, are 
isolated by transformers to prevent ground loops (aka Pin 1 
problem) .

If there is general interest I could put up a schematic, but 
it's a simple clean system that has great flexibility and 
never requires moving plugs. You can see the audio boxes at:

http://www.w8ji.com/my_shack.htm  for the house station.

http://www.w8ji.com/contest_station_w8ji.htm for the contest 
station

Since buss impedance is high normal CAT-5 cable makes a 
great audio buss. Each station, except the one feeding the 
buss, is isolated by transformers.

73 Tom