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jram 24-09-2012 14:20

SSB Tuner location
A friend of mine was on board a while back and pointed out that my Antenna Tuner (AT140) was positioned about 1 ft below the water line and this might not be a good thing.

Given the concept that we're trying to use the sea surface to reflect the transmitted energy, I'm tempted to move it to a location above the waterline but this will be a major task so before I set out can anyone advise how much difference its likely to make please?

Thank you!

JesperWe 24-09-2012 14:38

Re: SSB Tuner location
The location of your tuner makes very little difference Radio-wise.
I am assuming that you have the grounding to water done properly and a long whip antenna or isolated stay.
If you move the tuner a bit (like half a meter or so) it will not change anything in terms of radio reach, but as your friend points out it could make lifetime of the tuner longer.

Another good idea is to check the tuner casing and make sure its really watertight, even tiny amounts of saltwater can cause failure, I happen to know from experience :-( (Mine was in the transom compartment, above WL but still exposed to salt dampness...)

S/V Illusion 24-09-2012 14:46

Re: SSB Tuner location
Recognize that the antenna actually "begins" at the tuner output so anything you have below or at the WL is compromised. Whether it actually makes any difference isn't easily divined over the internet but probably not much if any.

phorvati 27-09-2012 12:51

Re: SSB Tuner location
I don't think it makes nearly as much of a difference as carefully and patiently laying out your counterpoise. If you're going to invest time due to suspicious coverage or weak signals etc, I would spend time in grounding.

SSB/HF Radio Applications in Modern Sailing Vessels | Pacific Cup

btrayfors 27-09-2012 13:51

Re: SSB Tuner location
As others have said, positioning the AT140 1' below the waterline will make no discernable difference to your signal output.

However, the cautions regarding saltwater-free locations are well taken.


jram 27-09-2012 14:44

Re: SSB Tuner location
Thank you all for your contributions - well received! The location is saltwater-free and the connections are all in good shape.

I take on board the views on paying attention to the grounding - I have about 15 ft of 4 inch foil between the radio and the tuner and a further 5 ft between the tuner and a Small Dynaplate. I am tempted to run a further length of foil to the main water tank to further increase the surface area or I could make up a bunch of radials as discussed elsewhere.

The reason I am doing this is that I want to improve my reception of weaker signals. It seems that my Tx signal is pretty good (although not as good as some others).

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