If anyone here has experience with the Icom AH-4 antenna tuner, I
have
a simple question. Is there any reason I can not extend the control
line beyond the 10 meter length that Icom supplies with a new tuner?

You can extend it, I have done so. If you extend it to ridiculous
lengths, or with thin wire, you can expect to mess up the ATU due to
voltage drop in the ground and +12 wires.

Owen



Thanks, Owen. I was just making sure before spending my precious
dollars. Don't expect to need control line more than 50 feet long... #
18 wire, I imagine.

Ed