Welding cable as counterpoise

[whatknot]

I would like to use my ham radio in my boat this weekend, the boat is a 1970 Columbia 36 and the radio is a icom 7200. I also just ordered a ah4 tuner for it and if it comes in before the weekend I'm going to take the radio to the boat. I have gto 15 for an antenna now just need a counterpoise. I have about 30 foot of welding cable from my old truck welder that is about the diameter of my thumb. Any ideas how to make that work or something simple for the weekend until I actually mount the radio and have time to put a proper counterpoise in. Thanks

[Cheechako]

My understanding is it's surface area that counts, so cable not the best, but it might work fine. People use narrow strips of copper etc that aren't that much area.

[whatknot]

That's my understanding too but hoping to make something work for the weekend. I'm like a kid with a new toy, the ah4 is ordered and should be here the next couple days and can't wait to play with it.

[ka4wja]

Whatknot,
1) A few brief pieces of fact that should help you out...

a) Oh boy, here we go again!!
(All the info you need is either in the sticky above or in the links there...
http://www.cruisersforum.com/forums/...tc-133496.html )
Remember you can make contacts with no ground at all, no counterpoise at all...
So, what antenna ground / counterpoise you have, and how well it works, is all a matter of degree!!

b) Building a counterpoise (artificial antenna ground / counterpoise) is the same on a boat as on land...(except that most on boats have a great advantage, and use the best "counterpoise" there is: the sea water itself, and it's the "connecting" to the sea water that we use a low-impedance connection to the sea water, and this is where the recommendation to use wide copper strapping comes in!!))

c) You do not need to use "welding wire" for a counterpoise....anything conducive works, even the sea water (actually the sea water is one of the best antenna grounds you can get!!)...
Copper is best....and as much of it, as close to the AH-4 as possible is best...
This does NOT mean lining your hull with copper!!
Nor, do you need to use wide-flat copper strapping, etc. as a counterpoise...
Round copper wire is fine....20ga or 18ga insulated is fine...
This is what hams on shore refer to as "radials"!!
(except for some serious 160m contest stations who have used copper strapping radials, no hams nor broadcast stations use these for radials...)


d) If you cannot make a short, low-impedance, direct sea water connection for an antenna ground...then many choose an artificial counterpoise as their antenna ground...
Many items on board are good for this:
-- Metal tanks that are close to the AH-4....
-- Pushpits, pullpits, arches, lifelines, alum toerails (attach under the anodizing), rub strips, etc...
These items all work well, and usually better than making up radials...

e) But, if you have bronze thru hulls (or an external grounding plate) that is close to the AH-4 tuner (8' - 10', or closer...closer the better), then simply using a piece of 2" to 3" wide copper strapping from the AH-4's ground lug to the bronze thru-hull, and you've accomplished the best oiverall, wide-band, antenna ground that you can have...
Total cost is usually about < $50 for the copper strapping...




2) If you cannot do "e", then do "d"....
If neither of those is do-able, for this temporary install, etc., then go with "c"...
Making as many radials as you can, and fitting them in wherever you can, and spread out as best you can....in the bilges, under the cabin sole, in the cabin headliner, under the deck, thru lockers/cabinets, etc...these are all viable places...

Their exact length isn't critical, as they will be de-tuned by both their close proximity to each other as well as everything else on-board, and especially by their close proximity to the hull and ocean ("earth"!)...
But, if you have some favorite bands (such as 20m and 40m??), then cutting them a 1/4-wave for those bands is fine....(16' and 33') and use at least a half-dozen of each...
If these are too long, no worries, just make 'em as long as you can fit...zig-zag, etc...but even then their length is not important, but the quantity is...more is better!!

If you want to see what you can do/make for free (or at most for about $5), have a look at this posting...(you can see the actual resonances, or lack thereof, of various wire radials in use)
Re: KISS-SSB Counterpoise

Originally Posted by whatknot

I would like to use my ham radio in my boat this weekend, the boat is a 1970 Columbia 36 and the radio is a icom 7200. I also just ordered a ah4 tuner for it and if it comes in before the weekend I'm going to take the radio to the boat. I have gto 15 for an antenna now just need a counterpoise. I have about 30 foot of welding cable from my old truck welder that is about the diameter of my thumb. Any ideas how to make that work or something simple for the weekend until I actually mount the radio and have time to put a proper counterpoise in. Thanks

I hope this helps...

Fair winds...

John

[Paul Elliott]

Yes, go ahead and use the welding cable. Stretch it out. This isn't good for a permanent solution, but with the tuner it's going to work well enough to play with.

Actually, depending on the frequency you want to operate on, 30 ft may be too long. This is getting close to a half-wave on the 20-meter ham band, and (if stretched out in free space) would appear as a high impedance and not a ground. For 20 meters, I would double the cable back and connect both ends to the tuner ground. If you don't mind cutting the cable, two 15-foot runs would be better, but for just messing around this shouldn't be necessary.

Longer term: Use copper strap or heavy foil to connect the tuner ground to a (bronze) through-hull, or keelbolt, or ground plate. You will find *plenty* of discussion here and elsewhere about boat RF ground systems.
[edit: see ka4wja's post above]

In general, welding cable isn't what you want to use on a salt water boat. The wire strands are very fine, and aren't tinned. They will corrode in a year or so. Don't use braid either (for the same reason).

[whatknot]

Thanks KA4WJA, I've been overthinking this so much that I have confused myself. I've read my arrl books and researched this but what you just typed helped me understand it better than hours of research! Hope to make some contacts this weekend. KD9HWU

[whatknot]

Thanks Paul. Just saw your comments. This weekend I'm going to use the welding cable at least Friday night and figure out a permanent solution on sat. At least I'll get to play on the ham (the wife is out of town for the weekend)

[ka4wja]

Whatknot,
Not to sound contrary, nor throw water at your plan...
But, if this is a temp installation and/or just for fun, why bring the welding cable?
Just grab some lengths of hook-up wire (any insulated copper wire), cut two or three pieces at ~ 16' and ~ 33' (approx. 1/4-waves on 20m and 40m), or whatever length you can fit, wherever you can run 'em....spread 'em out as best you can, either on-deck or below decks, and you'll be in much better shape than one 30' long piece of welding wire....and it will all roll-up into a small bundle...

Originally Posted by whatknot

Thanks Paul. Just saw your comments. This weekend I'm going to use the welding cable at least Friday night and figure out a permanent solution on sat. At least I'll get to play on the ham (the wife is out of town for the weekend)

Just saying you will get NO improvement at all whether you used 30' of 18ga wire versus 30' of welding cable....so why bring the big stuff that will be a pain to work with??





Oh, FYI...
For a finite amount of wire, more / shorter "radials" produce much better results as a counterpoise, than few/longer radials!!
What this mean is, if you have 100' of wire...make 8 - 10 radials, 10' - 12' long....rather than two 50' long radials....much better performance...
Now, on our boats, this usually isn't practical....and since we float on top of the best "counterpoise" available (the sea water), and most boats have adequate tanks, toe rails, lifelines, pushpits, etc....the use of radials on-board is usually just a last gasp effort....
But, in this case (your temp install), radials are a good way to get you going...


EDIT:
Just saw that you're in KY???
No sea water there!
So, please disregard my mention of "floating on the best counterpoise"!!
Fresh water is NOT a good RF / Antenna ground, NOT a good counterpoise!!
Most soil, even sand, is better than fresh water!!
Build some radials for your weekend operating, and you'll be fine!!
(if making a perm install, use toe rails, lifelines, pushpits, etc. etc., and the radials, etc....and you'll be good....if venturing into the ocean, then a direct sea water connection is best!)




Fair winds...

John

[Paul Elliott]

Originally Posted by ka4wja

EDIT:
Just saw that you're in KY???
No sea water there!
So, please disregard my mention of "floating on the best counterpoise"!!
Fresh water is NOT a good RF / Antenna ground, NOT a good counterpoise!!
Most soil, even sand, is better than fresh water!!
Build some radials for your weekend operating, and you'll be fine!!
(if making a perm install, use toe rails, lifelines, pushpits, etc. etc., and the radials, etc....and you'll be good....if venturing into the ocean, then a direct sea water connection is best!)

Oops indeed! My through-hull suggestion wasn't such a good idea for a fresh water boat. Follow ka4wja's advice. But while the welding cable won't be much better (it at all) than thinner wire, go ahead and use it if that's what you have handy. I kind of like the idea of spreading it out in a big 30-ft circumference loop and connecting both ends to the tuner ground. To me it just "feels" like that should be a broader-tuning counterpoise. Or it may make no difference.

[toddster8]

Hah, I was going to ask you experts about the (my) situation of being in a freshwater home port with occasional escape to saltwater. Perhaps eventually permanent. Of course, one doesn't really need long-range radio in fresh water, but that is where all the rigging and testing is happening.

Also, what dependent variable could be used for testing different counterpoise options? I think in previous discussion some of you said that SWR is not a good indicator of function? Assuming that we do not have an electronics lab at hand...

[Paul Elliott]

Originally Posted by toddster8

Also, what dependent variable could be used for testing different counterpoise options? I think in previous discussion some of you said that SWR is not a good indicator of function? Assuming that we do not have an electronics lab at hand...

I am looking forward to some discussion on this question, but until then I have a few semi-educated thoughts I will share:

• With a resonant antenna such as a tuned dipole, SWR is a good indicator. True, losses in the feedline will lower the SWR when measured at the transceiver, but you can figure out the cable loss by removing or shorting the antenna.

• With something like my backstay antenna with boat grounding system being fed by an antenna tuner, SWR will tell you if the tuner can find a match. Low SWR here is good, but at some settings a tuner can be quite lossy, and again, loss will hide a bad SWR (or lossy match, or lossy ground system).

• If you can find an R.F. ammeter and put it at the output of the tuner that should give you an indication if the tuner and antenna are doing a good job or not. I've never tried this myself...

• People have taped neon bulbs or fluorescent tubes to a backstay antenna and tuned for "maximum glow". The bulb location along the antenna wire is probably important. This is another technique I've never tried myself.

• You can use a field strength meter, or someone else's close-by receiver to give you a clue about your relative signal strength. More is better, but there's no practical way to calibrate this. I've done a lot of field-strength measurements using calibrated antennas, measuring receivers, and open area test sites as well as RF anechoic chambers, but at much higher frequencies where the dimensions are managable.

• We still haven't looked at antenna directivity patterns, propagation vs frequency, noise sources, etc. At some point you just fire up the transceiver, see if the tuner is happy, and start making contacts.

There is so much variability in all this that we often read reports from people boasting about the great performance of what (in scientific truth) has to be a lousy ground / antenna / whatever. The fact is that sometimes you can work around the world transmitting ten watts into a bent coat hanger for an antenna. Other times a kilowatt feeding a great antenna can't get beyond 100 miles. You might as well do the best job you can with your radio system, but most people will hit the point of diminishing returns pretty quickly if they follow a few simple steps.

[Lepke]

In the 70s a po used large welding cables between the helm and batteries (about 40') and the cables are still in excellent, shiny shape.
In the old days when most boats were wood, people put a copper plate about 3'x5' on the hull with a bronze carriage bolt thru the hull for a grounding point. I use to be able to buy 3" copper in a roll to attach the radio and lightning rods.

[Paul Elliott]

Originally Posted by Lepke

In the 70s a po used large welding cables between the helm and batteries (about 40') and the cables are still in excellent, shiny shape.

Well, I got my contrary information from a friend of a friend who knew a guy.

I do suppose the cable longevity depends on how wet things get, the state of the insulation, and how well the lugs are dressed.

[whatknot]

Thanks for all the advice, I knew fresh water is a poor counterpoise but hopefully soon the wife and I will be in salt water. I just received shipping confirmation that the auto tuner will be here Friday and after reading Ka4wja's post my radials from my field antenna should do for the weekend.

[ka4wja]

Lepke,
"in the old days"??
With 99% of cruising boats these days being fiberglass (GRP), the "old days" are still here!
{You may not be one of the 99% of us, so just thought you might not be aware of these facts below...}


For "grounding points"

--- Lightning grounds:
You should be aware that the definitive work on "lightning and boats" (done by Univ of Florida professor) and recommended by the ABYC, does recommend an external grounding plate (although 3' x 5', is a bit more than I recall being required in fresh water, it is not far off....but, this is 10+ times more than needed in sea water)....and many just use their external lead keel (not the best for an HF rf ground, but lightning is mostly DC and low-freq AC, so a big blob of lead is pretty good!)

--- RF Grounds / Antenna Grounds:
While the ABYC isn't quite as definitive here, Sailmal, et al is!!
And, with Sailmail and HF marine radio manufactures (as well as just about every educated/experienced HF marine radio installer, and every ham who has ever designed/installed HF vertical antennas near/on sea water), and good 'ole Gordon West's definitive tests comparing various antenna grounds / rf grounds on modern fiberglass sailboats, etc. etc. etc....all clearly showing and recommending a direct sea water connection to use the sea water as your antenna ground / rf ground, but not needing anywhere near the 3' x 5' plate!!!

Here are pics of my "plates"....I have all Marelon thru-hulls, so installed Dynaplates (18" x 6", each) and used 6" wide copper strap (about 8' long), as well as some 3" wide copper strap to tie-in some tanks, and even ran a longer piece all the way to a keel bolt....
Yes, I'm a radio nut....

But, there are many, many sailors with fiberglass boats that utilize low-impedance (copper strap) direct sea water connections for their antenna grounds....those with bronze thru-hulls have it pretty easy, and most use them....those of us with Marelon, use external plate(s)!




(sorry about the corrosion on the copper strap, but hey after a dozen years, it does start to look old.... (but the parts that I painted/covered, still look great!)

Originally Posted by Lepke

In the old days when most boats were wood, people put a copper plate about 3'x5' on the hull with a bronze carriage bolt thru the hull for a grounding point. I use to be able to buy 3" copper in a roll to attach the radio and lightning rods.

And, if you're looking for a place to buy clean, high-quality copper strapping....I've been doing business with Georgia Copper for many years...Great guys!!

GEORGIA COPPER - Copper ground strap

GEORGIA COPPER - Copper ground strap


I hope this helps...

John