Icom AT-140 antenna location

[Caroline Joan]

I have installed new Icom 802 SSB at navigation station which is roughly midships. My yacht has never had a SSB before.
I have a new backstay with insulators fitted.

The problem i'm having is a location for Icom AT-140 auto antenna tuner. Instruction book says install outside close to antenna. Is outside necessary - I think it only says that as its fully waterproof.

I don't have anywhere suitable outside, plus i think it would be easy to damage.

The only suitable place i can find is in the cockpit STB wet locker.
This would mean approx 3 metre aerial wire to backstay.

Possible problem is it would be located 150mm from shorepower 240 volt isolator switch & 500mm from diesel generator. Would this be a problem.
This location would also be approx 1.2m from compass.

Your advice would be greatly appreciated!

[smac999]

A laz looker is common. Outside on a sailboat would be silly. more sense on a big boat with a bridge

[chuckr]

we have a Jeanneau DS40 and put our tuner all the way in the back of the boat - right next to where the antenna wire comes in - our radio itself is midship and we run copper stripping down the hull of the boat and it works great

[GILow]

I put ours on the lazarett cabin roof, as far aft as I could go, kept the run from the tuner to the backstab nice and short. Ran the ground plain to the cockpit drain skin fittings as they were nice and close. Seems to work ok but early days yet.

Matt

[Flint]

Theory is that your are tuning the "feed point match" of the antenna, which is what you want to do for the best signal out of the antenna. Putting the tune beside the radio will work from an impedance match point of view because the radio will see a perfect 50 ohm load attached, but the antenna itself has not been corrected - just what the radio sees.

Radio, like sailing is often full of compromises. Avoid proximity with the generator. You could end up with a lot of noise coming into the receiver.

But in the end, try it and see. BTW, use high quality feedline. LMR400 flex.

cheers
David

[svHyLyte]

We have a somewhat older ICOM SSB than your 802 working with an earlier AT120 Tuner. In our case, the Tuner is situated in our starboard stern locker, up under the side-deck similarly close to an AC power cable junction and not far from our 4.2KW generator as you describe. The cable run from the Tuner to the back-stay antenna above the lower insulator is about 9 feet. With this arrangement our radio works quite well. From time-to-time I do have to shut down some of the gear that seems to generate "noise", primarily some of the lights that use fluorescent bulbs and one of the refrigeration units but that is no great handicap. (In no case would I have a Tuner installed in the weather!)

FWIW...