[Elecraft] K2 to antenna Power

[k7hbg at dslextreme.com]

Good evening Elecrafters, may your Monday be a restfull one!

 I would like to send a low voltage limited current up the coax from my K2
to the antenna for powering a small device. What would be the best way to
inject this voltage into the antenna feed (coax) at the K2 and recovering
it "up the stack"? I was hoping to continue supplying this voltage even
while transmitting 100 watts.
 I thought that the transverter manuals might have some advice about
powering preamps but, not a word.

 Best regards, Bob K7HBG.
K2# 2836 which "Will only be pried from my cold dead fingers"