Jim : Go to Radio shack. Get a small 12V relay with external contacts
that close when relay energized. Use the 7 pin DIN connector and put
pin 1 (12v) and pin 3 (ground on xmit)to the relay coil. On xmit you
will be keying the relay which in turn keys the linear. The relay
output of the RS relays will tell you what amp capable of handling.
Most are good for up to 2-3 amps and up to 24 volts from a linear, in
fact can key 110v linear relays OK too if about 200ma or so.. These
relays are cheap. Do NOT buy the Icom device, you will pay $25-30..
San