Ham radio operators please read

[k1vsk]

I'm looking for some experience in eliminating radiated RF hash from adjacent boats in the marina.

Specifically, I have eliminated or minimized to the extent practicable all conductive noise sources from my boat such that away from the dock, the noise floor on HF is nil. However, upon returning to the marina, it returns regardless of whether we're plugged in. This leads me to believe it is radiated from adjacent sources (not a genius deduction, I know) but the description of my thought process might be of some help. Having effectively isolated the DC and Rf grounds and installed a large surface area counterpoise, I have gone as far as I can in terms of the installation on my own boat and eliminated all self-inflicted noise sources.

Since I have no clue which is the offending boat(s), I seem to be left with the option of buying or building some noise attenuation filter as a last resort and was wondering if anyone here has any experience in this area which is somewhat unique to typical HF radio home station issues.

Anyone else faced this problem successfully and if so, how?

[jerryrlitton]

Do you have a steel hull?

[Sailormann]

Specifically, I have eliminated or minimized to the extent practicable all conductive noise sources from my boat such that away from the dock, the noise floor on HF is nil. However, upon returning to the marina, it returns regardless of whether we're plugged in. This leads me to believe it is radiated from adjacent sources (not a genius deduction, I know) but the description of my thought process might be of some help. Having effectively isolated the DC and Rf grounds and installed a large surface area counterpoise, I have gone as far as I can in terms of the installation on my own boat and eliminated all self-inflicted noise sources.

Since I have no clue which is the offending boat(s), I seem to be left with the option of buying or building some noise attenuation filter as a last resort and was wondering if anyone here has any experience in this area which is somewhat unique to typical HF radio home station issues.

Anyone else faced this problem successfully and if so, how?

Hmm - well assuming that you have shielded everything except your antenna, your ground is good, and that the ground for the AC circuit your boat is plugged into is good, and there is no leak to or from the galvanic isolator...

You are probably getting echo noise. I would suspect radar reflectors, as they will reflect harmonics at much lower frequencies than the radar bands. Also, tall buildings, particularly the skyscrapers with the metallic coatings on the glass will send echos all over the place.

Is it important to use your HF at the dock. Could you try a telephone instead ?

[SYMandalay]

We believe that there are locations with a large military presence (Coast Guard, Navy) that are always going to have noise originating from their communication equipment. Not much you can do....

[chuckjohansen]

Most of the HF RFI comes from marine refrigerator compressors. Not much you can do about other boats emitting noise. Our CW (WaterWayRadio & CruisingClub 7.050 7AM EST) net folks just went through a long E-mail string about such offending boats in anchorages and which marine compressors are the least noisey and most noisey. Sorry for the bad news.

Chuck
SV "Phrophecy"
K2VQ

[jerryrlitton]

I was thinking if he had a steel hull and the were some leakage of stray "trons" in the water that may be a source of the problem. Just my .02 worth.

[k1vsk]

thanks for the replies -
glass hull,
refer compressors are a known problem source of radiated noise but hard to believe since the noise level is constant,
no other strong Rf sources in vicinity,
radar at a marina is not likely, and
thanks but I'd rather not call S Africa on the telephone.

73

[RealityCheck]

Originally Posted by k1vsk

thanks for the replies -
, and
thanks but I'd rather not call S Africa on the telephone.

73

I use Skype when WIFI is available and the cost is a few cents a minute. Local interference doesn't seem to hinder it.. diff op freq and conditions

[jerryrlitton]

www.skype.com
I use it when I am in Alaska calling the lower 48 and Canada. .02 a minute and you get a phone number so you can be called and they can leave a message when you are away. All you need is broadband and you are set.

Jerry

[SEMIJim]

Originally Posted by k1vsk

refer compressors are a known problem source of radiated noise but hard to believe since the noise level is constant,

It's a marina, right? Lots of boats, right? Unlikely all their compressors would cycle to the same beat, right?

Originally Posted by k1vsk

no other strong Rf sources in vicinity,

What do you mean by this?

Besides: The noise source(s) needn't necessarily be "strong." RF signal strength varies inversely with the square of the distance (inverse square law). A very tiny noise source close-by can be much more devastating than a very big noise source further away.

You know: The odds are probably pretty high that just about every other boat in that marina, and every occupied building nearby, has something running, right? A lot of those somethings will contain RF noise generators these days. Anything with a CPU in it, a motor in it, an SCR (e.g.: light dimmers), etc., is likely to generate noise. You know radio receivers emit a small amount of RF energy themselves, right? Then there's harmonic and sub-harmonic interference from other transmitters. No power lines nearby?

Originally Posted by k1vsk

radar at a marina is not likely, and

After watching boat-after-boat-after-boat go down a 100' wide canal in the middle of the day in sunny weather with their radar running to beat the band, I wouldn't be so certain.

Originally Posted by k1vsk

thanks but I'd rather not call S Africa on the telephone.

Internet VoIP phone?

Have you tried grabbing an inexpensive portable AM radio and walking the marina to see if you can identify the noise source(s)? Had an inexplicable noise at one time. Tracked it down this way. Turned out to be an electric blanket. (In our own home, thankfully.)

An any event: There's little you can do at your end. RF noise is RF, just like RF signal is RF. Some receivers are better at suppressing/filtering it than others, but none can get rid of it entirely.

Originally Posted by k1vsk

73

45

Jim