counterpoise layout

[Wahoo Sails]

Rick & EngNate,
I have 2 other sources of info on this SSB installation, Ken & Steve. Ken is a certified radio technician with a ton of knowledge ... although not necessarilly boating specific. Steve is ABYC certified, has been to school for SSB installations and is widely recognized as the best marine electrician in the area ... so I have 4 sources of information.
On the subject of Dynaplate instead of counterpoise I have 2 "yea" one strong "nay" one no comment.
On the subject of insulating the backstay I have 2 strong "yeas" 1 "nay" one "stick with the long wire antenna".
On the subject of connecting the tuner to the Dynaplate, I have one "use bundled parallel wiring" 1 "use copper foil", 1 "don't use the Dynaplate" 1 no comment.
Geeeeeez .... and I was hoping to CLARIFY the situation!
Bob & Lynn

[GordMay]

I can empathise!
I used to think I had an opinion, until I started to learn a little more about the subject.
I now know enough to know, I’m not qualified to have an opinion.

Rick & EngNate are presenting an interesting, though not yet fully enlightening, discussion on the underlying theory.

[EngNate]

Did I profess anything about physics? Who cares who published a reference I cited "for example", when the contents are the same everywhere? Anybody else heard that the basic electronic laws and formulas had changed with the computer age? Why express condolances to me? You have no idea how well I've got it made...

The attached is from the Icom IC-M800 instruction manual, and should be informative to all - even I was enlightened somewhat...

[Rick]

All radio technical concepts are based upon known physics. I used to work for ICOM and am very famaliar with the SSB installation recommendations. There are several areas of misinformation contained therein that a few of us took exception to with sound physics arguments. Those individuals who wrote those manuals were not the most technically proficient yet were in the marketing position to write them without first checking with "others" in a better position of knowledge to verify the details.

For example, in the M800 manual it is stated that a round conductor should never be used for a counterpoise. Just open your brain for a second and think critically; If that were true then how could one use a round conductor for the radiator????? It just plain is not true and I challenge anyone to prove it using the laws of physics. Geez, most HAMS know that any 200W PEP transmitter will generate a fine output effective radiated power using round 12 GA wire as a radiating element. Smaller than 14 GA gets to be a problem and we're talking here about a single conductor.

Think, man, think!

[Rick]

in addition, take a look at antennas used around commercial VHF and UHF installations on buildings (like for police). You will see ROUND vertical radiators and several ROUND counterpoise radiators placed radially at right angles to the vertical main element. Those ROUND radiators forming the counterpoise are sufficiently close in angle so as to approximate a closed disc "ground" for transmission.

[Wahoo Sails]

OK guys ... Like many reading this thread, I don't know a thing about the physics involved in this ... and unfortunately I don't have the time to learn them. I believe that in all likelihood BOTH arrangements would work and that a neophyte like myself would be hard pressed to tell the difference in the end usage. Having said that, I have decided to try the connections as described by Rick ... my reasoning is that his is the simpelest and easiest to install. If for any reason this dosen't work to my satisfaction ... well? I'll post a new thread!
Rick,
The connection between tuner and Dynaplate .."multiple parallel wires" ... remember, I'm a complete dummy here, what kind of wire (s), how many? and what kind of terminations on them? Same question for the tuner to backstay connection.
I am at this point a little concerned about "driving the rig" without insulators ... but ... with only 2 of us aboard, it should be something we can do safely (I'll put a warning notice near the transciever to remind us) and besides ... it may end up being a convienent way to keep birds off the boat!!!
Bob & Lynn

[Rick]

Yes, one of the reasons for my suggestions is that one ought to try the easiest, most convient method for creating an antenna first, time permitting, in order to perhaps be pleasantly surprised by good (or even great) results.

Use "ordinary" marine grade ac wiring like 14-2 or 14-3 to obtain the desired number of conductors. If, for example, you figure that you need 5 conductors use a 14-2 and a 14-3 OR/ use two 14-3 cables (more is better yet don't get carried away with too much "more" because it merely costs you more) and marry them together every 10 inches or so with tie wraps. You WANT these wires to be as intimate as possible in order to take advantage of mutual inductance gained by having the conductors very close without electrically touching. Think of a copper foil as being a series of side-by side conductors without being insulated from each other. In that case you get no mutual inductance benefit.

Strip the ends and terminate them in a ring terminal which will accept all of the wires. You may wind up with a terminal that has a ring diameter much larger than the fastener upon which it goes. In that case, use bronze or copper washers of appropriate size so as to make good electrical contact with the fastener (which should have a "bottom" shoulder consisting of a boss or another washer anyway). IN the case of ICOM tuners they provide S/S washers. Replace the S/S washer with bronze or copper. Keep in mind that stainless steel is about 50 times less conductive than copper or bronze and, therefore, is not good for carrying current. You will apply a protectorant over the end result to keep everything pristine.

It is easier to terminate the tuner "output" wire using a ring terminal placed on the lowest fastener inside your boat that attaches your chainplate. If not, or when using S/S rigging wire to "jumper" over toggles, etc., serve the wire placed parallel with the stay. Cover the serving with 3-M electrical protectorant (comes in a can that even Home Depot sells). Do not tape over the connection or use anythig like that that cannot completely prevent salt water from entering the connection via wicking through the gaps between the stay individual wire strands. Do not use ANY type of silicone sealer, it ultimately will fail because if its lack of ability to adhere to stainless.

If the rig happens to facilitate a reasonable SWR at the frequency that you desire you will generate an effective radiated output power and communicate well. If not, then you may opt to investigate other means of making up your antenna but first check all bands of frequencies that you desire to use. The easiest manner to check for this is to place an rf ammeter on the tuner output wire to see just how many rf amps are going into the wire. You probably will not do that and are left with attempting to communicate with some distant station as a check. If you are in a marina with many masts around then they will affect your ability to communicate even with an ideal antenna so keep that in mind as well as to be aware of bluffs, buildings, etc. which will also negatively affect you.

A HAM friend may have an SWR meter to offer as a check yet measuring the SWR (this measurement is valid only at the tuner end of the transceiver coax, not the transceiver end unless the coax length is exactly a half-wave multiple in electrical length AT the frequency of measurement...many HAMS and installers do not realize this fact). Anyway, the SWR reading only tells you that the tuner has achieved a match between its internal reactive components and the impedance seen at the end of the coax thereby allowing the transmitter to output power without automatically cutting back due to a mismatch. It can happen that you can put out 200 Watts of peak power from the transceiver and put out nothing into the antenna, the power gets absorbed by the internal "matching" components of the tuner.

During the tuning process the AT120 only "tells" the transmitter to use a few Watts. After a tune is achieved then the transmitter will ouput as much as you drive it as long as there is no poor SWR to cut down the power (that the transmitter has built in to save it from damage in case of a bad match).

Some installation may work well on 4, 7, 8, 12, 14 MHz and not at all on 16 and then fine on higher bands....you just don't know in advance with a particular boat. This is an easy thing to try without cost, only effort. If you determine that your particular "antenna" is not sufficient THEN use a different approach, yet leave the tuner and its "ground" as is.

If your "antenna" happens to appear to have quarter-wave-like lengths at your frequency of operation then the voltage at and near the tuner is minimum, the current is maximum, therefore, there is little to fear from if one were to touch the radiator. Even with a bad match if you were to touch the wire you could get a slight burn which turns the skin white. You will not be shocked and your brain and liver will not get fried. The worst problem with getting an rf burn is to feel the pain and jerk back causing collateral damage so that is not good.

More later if you have questions. Hope this helps.
Regards,
Rick

[Rick]

BTW: If you have a wire topping lift it will affect the "antenna". In fact, one method of tuning the "antenna" consisting of you backstay, mast, etc. is to attach a wire to the top of the mast and vary its length and angle relative to the backstay. In some cases I have been able to achieve a "perfect" tune on 7 and 14 MHz by doing this. The result might be a 14 GA wire electrically attached to the top of the mast and about 30 degrees away from the backstay and terminated about 7 feet above the port side of the stern pulpit where it is attached using clear fishing line. That way the tune wire happened to be out of the way of the boom, etc.

So, first try a tune using all bands with your topping lift detached from the boom and place it against the mast. Then attach a line to the end of the lift and move it around and vary its length. All the while you need to place the AT120 in the "bypass" mode and use an SWR meter at the tuner end of the coax to observe the effects. More on this later if you should get into it.

If the metal topping lift has a bad "tune" effect replace it with a high-modulus line (which will be small in diameter and easier to deal with anyway).

[WindDancer]

Rick, what if a radar is mounted to backstay at the Y? Are all bets off to have connection at chainplate with only one insulator at mast end of backstay?

Thanks for interesting thread
Forrest

[Rick]

No, all bets are not off with a radar on the backstay. The proximity of the radar and its cable will sap some of the magnetic flux from the stay yet it will still work at a decreased efficiency.

Modern radars have very good rejection to the SSB interferrence in terms of damage...one might have some display problems during HF transmission as a bother.

Your description sounds like a split backstay, is that true? IF so, that poses another efficiency loss but, oh well, what can one do?

[WindDancer]

Yes, it is a split backstay. I don't know if I should move the radar to a mast or install an "Outbacker" antenna without the tuner(less expense). Even toy'd with idea of installing an insulator in top of one of the shrouds and loading into it, but have been advised that could be dangerous(higher stresses could break the insulator).

Forrest

[Wahoo Sails]

Rick,
I do indeed have enough 14/3 laying around to make the tuner to Dynaplate connection. Oddly enough found some bronze nuts & washers at work and brought them to the boat ... sounds like that will work there as well. I didn't see a mention as to what type of wire to use for the output to the chainplate ... should this be made with the 14/3 as well?
I'm sure this will disappoint many following this thread ... but I will not be getting to this project for some weeks to come. We're just finishing up our exterior brightwork (every piece of wood had to be stripped bare) and are currently working at our steering station. I'm 10" taller than Lynn, so I'm building a platform for her to stand on when steering ... also adding a helmseat with a removable spacer for her so that it will accomodate both of our heights. I have just installed a Standard Horizon PS 1000 DSC/VHF with the RAM at the helm & will be installing a new CP175C at the pedestal guard. Oh yeah ... recutting & repairing our main, making a new genoa .. new dodger/bimini and a dozen other little projects ... like the WiFi amplifier ..... hey ... had planned to relocate our WiFi antenna to a shroud, though it will have an insulated mount there ... will that be a problem? Both the tuner & Dynaplate are in our 1/4 berth .. which is currently crammed full of sails & materials ... will work on them as the opportunity presents itself.
Thanks a bunch for the info.
Bob & Lynn

[Rick]

WindDancer: If you already have the automatic tuner I suggest trying to drive the chainplate (again, inside the boat where the tuner is protected and out of sight and closer to the sea water) to one of your backstays making sure that the other backstay chainplate is not bonded or connected to lightning ground. Check out the results on all freq. bands THEN if the results are dissappointing use another method.

Check out Brion Toss Rigging: briontoss.com and contact them for a conservative opinion on an insulator that is KNOWN to not fail or degrade your rig's integrity.

Wahoo: Merely use the "high-voltage" thickly insulated wire that comes with the AT120 (because you should already have it) for the tuner output. Note that the radiator of your "antenna" begins at the tuner output by definition and, therefore, merely has to be some wire which will capably carry the rf current having physical characteristics similar to the rest of the antenna. If necessary you can use a single #12 GA (or larger) insulated wire. The high voltage rating of the supplied wire and insulator located on the top of the tuner is overkill for a 200W PEP transmitter but so what?

Both: If you drive your rig via a chainplate that is grounded you might opt to place a knife switch in line with the ground wire so that in a lightning storm you can throw the knife switch closed for added protection. If you inadvertently transmit into the ground it will not damage the tuner or the transceiver because they are protected by design from that misadventure. They are NOT protected from lightning damage which has caused the most destruction of those units that I have observed over the years.

[WindDancer]

Thank you for the info and your patience with my questions.

Forrest

[phorvati]

I thought i knew few things about RF gronding and a ham/SSB rig, but after I read this thread I am confused.
(un)Fortunately major task is done(probably a waste of time). Few weeks ago i have finished glassing-in 100 feet of 6" coppper strap under bunks, watertanks, and in lazarette. Having aluminim toerails I tied those as well via large washers to the fasteners. The foil ends at the keel bolt(I have external lead keel). Next and final haul-out(before we go cruising) I'll make sure that the underside of the lead keel is not painted. When I bought the boat 3 years ago, electrolysis ate up the mast step(keel stepped mast) almost completely due to previous owners negligence. Learning from that I bought 15 ceramic disk capasitors .1uF and I want to use 5 or so in parralel to bypass the copper to the keel bolt. Since this stuff will be sitting in the bildge is it ok to seal the entire capacitor setup in polyester?? Is there a heating problem in such a case?
Would I benefit additionaly by connecting the copper strap to the engine via the DC capacitor isolation or do you think the mentioned grounding sounds sufficient enough to try it out.
I have isolated backstay (2 isolators) and a new M710/AT130. Just tonight I finished soldering connector for inside the tuner and adding ferrite line isolatior at the tuner end of RG8U. Decided to use the big old coax and not the small RG8X.
I am also still confised as to the benefit or drawback of RF grounding the radio in addition to the tuner?
Thanks,

Petar