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Old 25-09-2020, 14:39   #16
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Re: SSB ground to a copper strap?

I heartily second the use of a strap over braid for RF connections.
I have experience in the pulse power world.

Strap is ok. Braid is useless in that world.

With that kind of RF there is no such thing as a real ground. But strap gets you close.
Braid might as well not exist.
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Old 25-09-2020, 15:25   #17
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Re: SSB ground to a copper strap?

It astonishing how complicated and confused some people are over such a simple thing.

Ground is different than counterpoise. The radio and coax should be (and are) grounded by the negative battery connection

The antenna counterpoise can be any conductive material - it makes no difference! A counterpoise is essentially half of the antenna and, as with the antenna, can be any conductive material. Again, IT MAKES NO DIFFERENCE.

No amount of pontificating with academic mambo-jumbo changes the above.
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Old 25-09-2020, 16:34   #18
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Re: SSB ground to a copper strap?

The question was posed about internal ground capacitively coupled to seawater. I calculated the impedance (resistance to RF current) of a 2cm thick fiberglass hull, at 10MHz. I am assuming there is no air gap between the metal plate or foil, and the hull. The impedance is directly proportional to the material in the hull. There is a lot of variation in the dielectric constant in various tables, but it looks like the combination of glass and polyester resin has a Er of about 4. So for a plate of 1m^2 in a 2cm thick hull, the impedance at 10MHz is 10 ohms. That impedance scales linearly up with thicker hull or lower frequency, or down in the opposite case.
I would guess that 10 ohms is low enough to be significant, compared to having no coupling to seawater at all. Depends on how much metal in the boat is connected to the tuner ground and directly coupling to the antenna RF field without benefit of seawater.

If you're operating at 2MHz, that capacitance is probably not helping at all, while at 20MHz its probably useful.
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Old 25-09-2020, 16:39   #19
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Re: SSB ground to a copper strap?

While I use my centerboard pipe and stuffing tube for RF ground, this technique should work for thru hull. I tinned the end 4 inches of foil (longevity) cut a small cross slit a few inches from the end, wrap the foil around the tube and secure with a clamp that run through the slit.


The ground screw on the ICOM tuner is internally connected with a wire (I looked).


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Old 25-09-2020, 18:22   #20
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Re: SSB ground to a copper strap?

Probably not germane, but with experts on hand...

My system came with strap and a large (under the workbench, ~30x60") flat copper plate; those lead to the plate under the nav (but not connected to the M802), ~20-ish feet from the tuner.

The tuner is further connected to my arch and rails, with the gates bridged with a very heavy copper strap (more thickness than required, by far, but only about an inch wide.

So, I have, nominally, 200 feet of 1" tubing (top and middle) plus 12 stanchions 30" (30 lineal feet) also 1", and a great deal of 2 and 1.5" tubing in the arch. A massive amount of surface area - if it makes any difference...

That has seemed to make a very effective counterpoise. My question is: does all that rail/tubing, electrically connected to the tuner, help, hinder, or irrelevant?
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Old 25-09-2020, 20:19   #21
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Re: SSB ground to a copper strap?

Seawater is a great ground/ counterpoise. Best way to make the seawater connection highly variable and widely discussed. Railings, lifelines, internal copper plates all work just a matter of how well and at what frequency.


Many years back I talked coast to coast on a coat hanger out my bedroom window. Worked but did not choose a coat hanger antenna for my sailboat HF antenna.


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Old 25-09-2020, 21:50   #22
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Re: SSB ground to a copper strap?

Quote:
Originally Posted by foojin View Post
I’m sure this has been dealt with somewhere, but I couldn’t find it.

Contrary to the good advice here, this spring I was running out of time with many projects and purchased a KISS SSB ground before setting off cruising. Not sure about transmission, but reception was about the same with it or without it as John (ka4wja) and others assured me it would be.

Anyway, I will now install a copper strap between the tuner and a seacock, about 3-4 feet apart. My question is how do I attach the strap?

I have read that the strap should be “clamped” to the seacock. Not sure what that means, but wouldn’t it be better to drill holes at each end of the strap and fix one end to the screw at the tuner ground and one on the seacock normally used to ground DC circuits?

Advice appreciated.
There is no way I would be attaching to a seacock. The last thing you want is one - to weaken/stress the seacock with tightening a clamp around it, and two - to have it as part of another earth system, risking corrosion.

If you do not already have an earthing plate such as a dynaplate nearby, then it is a very good investment, and just involves two 10-12mm mounting holes. OK, you will need at least the stern out of the water to do it, but if you have a grid somewhere handy, that job can easily be done between tides.
If that is too hard where you are, keep using the KISS system until you haul..
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Old 26-09-2020, 07:16   #23
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Re: SSB ground to a copper strap?

Read this
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Old 26-09-2020, 09:45   #24
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Re: SSB ground to a copper strap?

Quote:
Originally Posted by skipgundlach View Post
Probably not germane, but with experts on hand...

My system came with strap and a large (under the workbench, ~30x60") flat copper plate; those lead to the plate under the nav (but not connected to the M802), ~20-ish feet from the tuner.

The tuner is further connected to my arch and rails, with the gates bridged with a very heavy copper strap (more thickness than required, by far, but only about an inch wide.

So, I have, nominally, 200 feet of 1" tubing (top and middle) plus 12 stanchions 30" (30 lineal feet) also 1", and a great deal of 2 and 1.5" tubing in the arch. A massive amount of surface area - if it makes any difference...

That has seemed to make a very effective counterpoise. My question is: does all that rail/tubing, electrically connected to the tuner, help, hinder, or irrelevant?

Having all that tubing connected to the ground is probably helpful.

I assume your 30x60" plate is internal to the hull. What about the one under the Nav station, is that external?

At higher HF frequencies that connection from tuner to plate under nav station has a bit of impedance. Ideally, and its an easy job with boat out of the water, you could add an external plate just under where you have the tuner. In my M46 I put the tuner over the wing tank which is in the cabinet at aft end of passage between main and aft cabins. I added the biggest Dynaplate almost directly below that, where internal access is easy by means of the hatch in the floorboards. Copper strap from tuner to plate is about 6' long by 3" wide and I tied that aluminum wing tank to the ground also.

Like you I connected the tuner to lifelines. The tuner ground is connected to the bolts from the stanchion directly above it and I removed the plastic sheathing from the lifelines where they pass through that stanchion.

You want to run your antenna lead up from the deck as close to right angles to the lifelines as possible. It may not look "neat" that way, but RF does not respect "neat".

Almost always found that if I can hear an HF station who is not terribly busy, I can work him.


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Old 26-09-2020, 10:10   #25
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Re: SSB ground to a copper strap?

has this: stan honey on grounds been posted here? Stan is the man that someone like Larry Ellison, who could have anyone at all, turns to.
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Old 26-09-2020, 11:51   #26
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Re: SSB ground to a copper strap?

Quote:
Originally Posted by Brian.D View Post
Brian,

I've read that before... you might have sent it to me in an earlier thread/effort to cure my ignorance.

Gordon West is one of those who says: "Just clamp the foil to the through-hull, being sure to first clean up the contact area on the fitting with a wire brush."

Left me wondering why/how-to clamp; why not just screw it down to an electrical connection on a thru-hull?
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Old 06-10-2020, 18:15   #27
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Re: SSB ground to a copper strap?

Far from a Ham/SSB expert but always thought the counterpoise had nothing to do with reception, only transmission.


Originally just hung some 1/0 wire in the water and then got a KISS. Talked to stations in Russia from So Cal. (Friend with Ham license, not me).



Have you tried using the KISS? Just need to be out of a marina or area with lots of masts.



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Old 06-10-2020, 22:40   #28
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Re: SSB ground to a copper strap?

Quote:
Originally Posted by Moontide View Post
Far from a Ham/SSB expert but always thought the counterpoise had nothing to do with reception, only transmission.

Originally just hung some 1/0 wire in the water and then got a KISS. Talked to stations in Russia from So Cal. (Friend with Ham license, not me).

Have you tried using the KISS? Just need to be out of a marina or area with lots of masts.

Bill

RF is a two-way street, if you will. Anything in the antenna or ground affects a transmitted signal and a received signal at the same frequency equally, in theory. Caveat, interference from noise sources on your boat obviously won't affect your transmitted signal unless it is so strong it actually modulates your transmission. That is possible but unlikely, since your transmitted signal, at your boat, is millions of times stronger than the received signal or the noise. But that same noise can have a huge effect on the much weaker received signal.

If you have an antenna tuner, you'll find that if you first transmit a little on the frequency you want to listen to or close to it, then the tuner will optimize the matching of transmitter to antenna. After that, you'll have a stronger received signal at that same frequency, and nearby frequencies.
That's assuming the tuner had previously been used at a much different frequency.


I'm sure the KISS system or any similar arrangement of copper straps inside the boat works reasonably well at higher frequencies, say above 15MHz, and will still work to some degree at lower frequencies. But lower frequencies benefit by having more ground area, and that's where a direct sea water connection should really help. Reliable HF propagation these days is mostly below 15MHz.
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Old 07-10-2020, 07:42   #29
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Re: SSB ground to a copper strap?

Waterman46, thanks, just learned something.
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