AH-4 antenna tuner on motorhome

[N7GCO]

I am using a ICOM 706 MKIIG in my motorhome with a AH-4 antenna tuner and 102" whip. The results are terrible. The radio and tuner are good products, so I must be missing something in my set up.

I have the tuner mounted close to the antenna(6 inches). The antenna mount and the AH-4 are grounded to the motorhome frame with #6 wire (nearest ground point at 4'). The antenna and tuner are mounted on the front drivers side 4' above the ground. The AH-4 is mounted on the fiberglass side and the antenna on a heavy metal bar which is attached to the front end about 16" away from motorhome.

I am not sure what to do next to improve the performance, but I believe I should be getting better reception. Currently all I am getting is noise on 20 meter and occasional a very very faint signal.

Thanks for any help or suggestions.

[K0BG]

If the RV is fiberglass and has a ladder, you can use the ladder as an antenna. This idea was written up in the ARRL Antenna Compendium number 7.

As for you current installation, the ground lead is as important as the lead to the antenna. You should replace it with flat braid.

Any vertical antenna needs a groundplane to work against. Whether this is radials, a metal body or frame. That is to say, to act as the second half of the antenna. If at all possible, the whip should be mounted directly on the frame (insulated from it obviously), or frame extension. In other words, not on fiberglass!

Lastly, the antenna should be made longer if possible. While 8 feet works, 12 feet will work MUCH better. If you look over my web site under Antennas and under Auto-Couplers, you'll see what I did and perhaps it will help you.

Alan, KØBG
www.k0bg.com