The KISS SSB Counterpoise - Revealed ( with Pics )

[transmitterdan]

Originally Posted by Goudurix

There is only 1 way to get out of this: setting up a real standardised experiment on a fixed raft in saltwater, and comparing several RF grounds and counterpoises... a KISS, radials, conncection to the seawater, and off course several calibrated receivers/field strength measurement equipment direct path, skip path.
Too difficult, too expensive.

Jan

Somebody did that already:

http://www.kp44.org/ftp/SeawaterGrou...GordonWest.pdf

[transmitterdan]

Originally Posted by plebian99

We also talking about capacitors in the ground system. I wonder how long all these capacitor last or if they are working at all. Sticking non RF current rated capacitors in the ground circuit while the antenna tuner is going from one frequency to the other is a recipe for failure. I bet if I checked all these capacitors installed this way, they will all be blown. It takes a serious capacitor with RF current and voltage ratings to handle the abuse that they will be subjected too during a tune cycle from one frequency to the other. While paralleling capacitors spreads the RF current burden it does not spread the voltage burden which can be several kilovolts. While the intention is good the proposed solution and execution has not been wisely thought about very well. Trying putting one of these recommended capacitors in series with your dummy load. Make a pactor transmission for a few minutes on a high frequency like 14 mhz and see how long that capacitor last. On a 50 ohm circuit the voltage may well be within the 300 volt rating. On a backstay antenna with an antenna tuner, the voltage will be massive and it will blow these capacitors. The capacitors you should be using is something like HEC HT58 and HT57 doorknobs or some other RF current and voltage rated capacitor. Its actually a joke that someone could recommend a "Type X7R Monolithic Ceramic capacitor, 0.15uF, $0.91 each, Digi-Key part number P4911-ND." to be installed in the ground system path with a automatic antenna tuner. Lot of poor RF science in these forums. These are the capacitors you should be using not some mickey mouse 90 cent capacitor. HH58 Series 7.5 kVDCCeramic Capacitors On High Energy Corp.

There is no need for an expensive 7.5kV capacitor in the ground lead.

The voltage on the DC blocking capacitors cannot be several kilovolts. Ground current is less than 100A for sure and most likely less than 20A at the lower frequencies. The reactance of a 0.15uF capacitor at 2MHz is .15*3.14159=.47 ohms. So even on the highest current assumption 100 X 0.47 is 47 volts. If you put just 4 in parallel then the voltage is less than 15 volts. But X7R capacitors are lossy and may overheat if the current is high enough.

A good choice for the capacitor to use is an NPO or C0G ceramic type. Values of 0.1uF are ok and even 0.047 would be acceptable if 8 in parallel. Either leaded or surface mount style will work just fine. If you put 4-8 in parallel then the current will be divided pretty much equally and should work fine. Digi-Key sells 630V surface mount capacitors for less than $2 each in small quantities.

[SoonerSailor]

The capacitors in the pi network of the antenna tuner that pass the full RF current are nowhere near the size of those doorknob capacitors, and if you go so far as to open one up and take a look, you might be surprised at their relatively small size.

The point is that the voltage ACROSS these capacitors and those blocking DC in a ground system is not in the hundreds.

[plebian99]

With all due respect you have simplistic notions of how antenna tuners, their components and antennas work. All textbook simplifications that any decent RF expert should be able to fully understand if he or she was designing a robust fault tolerant system. The capacitor selection guidelines are mickey mouse engineering at its best. You using a random wire backstay antenna on most yacht. These antennas are typically voltage fed. In fact with the simple RF grounds used on most yachts, the current and voltage minimums/maximums are all over the map. The antenna impedance with the whatever ground system used can skyrocket towards the 5000 ohm level and like wise the reactance values can be extreme. Since neither of you guys can know what exactly each and antenna and ground system is you have no way of knowing what the current and voltage minimums and maximums are. The reality is with only 100 watts of power the voltage at the end of the counterpoise can be as high 3000 volts. I have set grass on fire and burnt holes in wood with 100 watts of power feeding random length wires. Ever wonder why Icom and many other suggest avoid using a half wave end fed antenna?The capacitors that you guys recommend have very poor transient voltage limitations and are easily killed. A SMT capacitor would just about be the worst capacitor that can be used in any part of the antenna system. This is before you start talking about static or lighting impulse damage. Another point too is that the RF current various with frequency and even 8 of the caps that you people suggest would be struggling to handle the current at the higher frequencies. They are not RF current rated capacitor. Put your 8 capacitors in series with a dummy load, transmit for 5 minutes and watch how they get. Been there done that!That HEC doorknob will have sufficient safety margin to handle any RF voltage and current typically encountered during normal operation and even during the tune cycle at full power. While antenna tuners may use these marginal capacitors they are not exposed to the full potential RF voltages and currents during the tune cycle because tuning is done at low power. If the components used in most antenna tuners are used at the full power voltages and currents they would fail. You guys need to get into the real world and build some test jigs and test your solutions before recommending them to anyone. Anyone who has had experience building RF matching networks and doing RF bypass work will know how fragile these caps are in real life. If I had an expensive aluminum hulled vessel, I would not trust its safety to a few cheap dollar and dime store capacitors made in china. I would get a real HEC RF rated high voltage capacitor that would give you a huge amount of safety margin. Why be so cheap with such a critical part? Sailors do anything for building safe, reliable and redundant systems on their yachts. Using such poor components that does not withstand technical scrutiny is really being very cheap. Using such cheap capacitors ranks almost as bad as using non tin plated wire. The only problem is that a crap capacitor can cause 1000's of dollars worth of hull damage. A HEC capacitor is cheap insurance that would handle all possible RF current voltages that would be encountered. It would also handle static lighting transients with a much higher safety margin. Notice to the KVAR rating you ever find a disc or SMT capacitor with a KVAR rating, you wont because they not meant for the kind of abuse that guys want to put them through. If you cant afford a HEC capacitor or you truly believe that its an overkill get some MICA Snubber capacitors like the CDE CD16 and CDV16 series. Now these are meant for RF applications they can high RF current and can safely handle transient voltages. You can get them in all value and many voltage ratings. If you open many new ham radio and military auto antenna tuners you will find these snubber capacitors used in all parts of the RF circuits. No you wont find mickey mouse disc ceramic caps in these heavy duty RF tuners. Who can argue against good engineering practice?

[transmitterdan]

There is no need to waste money on several expensive oversize capacitors in this application. The surface mount capacitors are rated for RF and the math dictates that they will work just fine. We do have a way of knowing the maximum current in the ground lead. Common sense dictates that the maximum current cannot be 100 Amps. How do we know that? Because we only have 150w PEP available assuming zero matching loss. And if the current were 100A the antenna resistance would be 0.015 ohms. No antenna can be that low loss and no tuner can match it. Plus things inside the tuner and the small GTO wire would burn up. That's not happening so I am confident in what I said that the current cannot be more than 100A. The reality is that it can't even be 20A.

If the antenna resistance should become 3,000 ohms the tuner will not be able to match it. That's why Icom says to stay away from that condition. But even if it could match then the current at 150W would be less than 1A at the tuner output. If the ground strap runs to a thru-hull (which is the reason for the capacitor) then the current cannot be much different. The voltage across the capacitor in such a scenario is miniscule.

I suspect you may be confused by the difference between the voltage at the output of the tuner or far end of the wire antenna and the voltage across the DC blocking capacitor. They are not the same thing. And if you put 8 of the surface mount capacitors in parallel and feed a 50 ohm dummy load with 150W PEP they will not even get slightly warm. The current in each capacitor would be about 250milliamps.

Lightning would damage the tuner and radio long before the DC blocking caps. Since they cost about $10 in total it's not worth losing sleep over. If lightning damages your electronics those caps will be the least of your worries.

[s/v Jedi]

KISS is the best there is! Cheaper than the capacitors some use for their cheaper solution

[transmitterdan]

Nick, you're killing me...

[donradcliffe]

RF capacitors are not rocket science and not expensive. I rolled my own with 3 feet of copper foil and a plastic bag.

[Goudurix]

Originally Posted by donradcliffe

RF capacitors are not rocket science and not expensive. I rolled my own with 3 feet of copper foil and a plastic bag.

Hi Don, that sounds like and interesting DIY project.

I do have about 15 caps in parallel , I would have to check their voltage rating but remember I did have to search to find them.

Can you please give some details on the capacitor you've "rolled"?
?

Thanks,

Jan

[Argyle38]

Originally Posted by transmitterdan

I would not think it a great idea to connect the SSB tuner ground to a water or fuel tank. There isn't any need for that. Connect the SSB tuner to a convenient thru-hull with a copper foil (wider is better). Some tuners have built in DC isolation so check your particular choice to be sure. If needed then use the capacitor trick to block DC from the tuner ground.

Copper braid can work but it has higher loss than simple copper foil. Braid is not easy to terminate properly. Stick with foil for best results.

Thanks for the reply. I'll definitely stick with heavy duty foil such as the stuff that has been linked in this thread.

As far as RF grounding goes, the waters are still just as muddy as ever. What you say sounds perfectly valid and reasonable, both scientifically and logically. The PDF you linked to is also convincing and both you, the author of the PDF and others that recommend direct seawater grounding, all seem to know what you are talking about. However, this guy also seems to know what he's talking about:

Originally Posted by MagicSailor

All my own installations used to have either acres of copper sheet or mesh or connections to large metal tanks. Usually many hours of work and usually more than the price of the Kiss in materials. My own boat still has acres of corroding copper sheet under the settees. Apart from the Kiss, these are the only kind of ground planes I've come across that have always worked consistently whether I installed them or they were already in the boat. Most of the installations where I found the ground plane needed improving had copper strap to either a through hull or a dynaplate. I have never installed such a ground plane and never recommended it.

Will the Kiss work better than a well installed ground using acres of copper sheet or mesh, copper foil to metal tanks or 1/4 wave radials cut and spread out so that they don't detune each other? No, I don't think it will, but in my experience it does consistently work better than dynaplates or through-hulls and it's a heck of a lot cheaper than paying my hourly rates for installing any of the alternatives. And - it doesn't corrode.

Owen,
Yacht Magic
St Maarten

Thus is my dilemma. I do all of my installations myself. I'm willing to spend a few bucks on good quality copper foil and a few hours running said foil to where it needs to go if it means I'll have the best performing and most robust system that I can install. I have a background in physics, so concepts in capacitive coupling, inductance and RF antenna operations, etc. are familiar to me. But this knowledge doesn't help much in predicting the best practical solution in the complex marine environment.

For instance, I'm initially reluctant to RF ground to a thru hull because right now all of my thru-hull's (bronze) are bonded together. The DC ground bonding runs through the boat and is attached to a Dynaplate that is also electrically attached to the standing rigging, engine block, and, house battery negative. If I remove one bronze thru-hull from the (DC ground bonding) circuit to use as a conductor for the RF ground to seawater, will not that (now isolated) thru-hull act as an agent for electrolysis with my other thru-hulls, prop-shaft and propeller? I have had no problems with electrolysis so far so it seems that pulling a submerged metal out of the circuit would be inviting trouble.

It is for this reason, along with 'MagicSailor's' (and others I've read about) experience with direct seawater RF grounding that lead me to the opinion that a capacitive coupling to the surrounding would be just as effective. The PDF from Gordon West shows that in his installation, he attained quite superior results from direct coupling vs. capacitive coupling. It's a good and well written paper but I've heard of other anecdotal accounts that say the opposite. Perhaps it has to do with installation. Who knows.

I guess in summary, my follow up questions would be: Would removing a single thru-hull from a bonded thru-hull system contribute to electrolysis? What do you make of the comments of 'MagicSailor'? Simple disagreement, not your experience, or is it more that he is talking about RF ground failures where a good installation would not yield such issues? In other words, do you recommend a thru-hull because you feel it's a better RF ground or because it's an easier installation? I guess that is the most pertinent question in my rambling post.

Dear god... I though picking a new anchor was tough...

[svclanguage]

An isolated through haul has less chance than bonded one of having electrolysis issues as there is less chance for current flow. Not clear to me why some boats have them bonded, perhaps to provide path for lightning.

Icom tuners have non-isolated RF ground, while sgc has cap coupling, don't know about the others.

There is nothing wrong with connecting RF ground to existing protection and DC ground assuming the DC ground has good common grounding point to avoid unwanted current paths with high current loads such as engine starting, inverter and charging. If unsure then DC blocking capacitors are recommended at least at the tuner.

Installation of RF ground can be done incrementally, do the easy stuff first avoiding too good to be true solutions like Kiss, then add if you suspect your performance is less than optimal. This determination takes a long time and only way I know of to do it is to compare your ability to be heard by and to hear other station to other boats.

[transmitterdan]

I agree. Don't worry that the thru-hulls are bonded. Use the capacitor trick unless using the SGC tuner with internal DC blocking. The foil does not have to be heavy to work. The thickness is purely a matter of mechanical longevity. The width is the most important dimension. I like 50mm or more in width. Length is next most important. Shorter is better. Go to the closest submerged thing such as the dynaplate.

It's possible to have problems with any ground system. The marine SSB band covers quite a range in frequencies. There is a good chance some cable or foil length will be resonant at a desired frequency and performance will either be much improved or degraded depending on the interactions. This is why it's important to have either a basic grasp of RF or listen to people that do.

Your biggest problem will not be ground preventing reaching your intended contacts. Rather your big problems will be in identifying and eliminating the interference to on-board electronics such as auto-pilots, instruments, computers, LED lights, refrigeration, battery monitors and several more I can't think of right now. Then there's the interference from some of those devices into your SSB receiver. This needs to be checked thoroughly across the various bands. You will not be able to eliminate all of them so you have to pick your battles. My advice is to install something simple that is based on common sense so it ought to work (i.e. does not rely on magic beans). Then get on to the really interesting (hard) part.

[donradcliffe]

I think even the experts will agree that if you take a roll of aluminum foil, connect one end to your tuner ground lug and roll out the rest over the side into salt water, it will make about the best ground available.

If you are concerned about the effectiveness of your ground, establish a distant contact and get several signal reports (remember that atmospherics can also affect signals) with and without the aluminum foil connected. If there is no difference in the reports, there is no need to improve your ground system.

[mub]

My experiment...

Inspired by the kiss and the fact that my counterpoise ( no swearing please ) was 150mm of corroded 50mm wide copper tape and having just pulled out of the boat about 600ft of 16 guage un tinned copper.

The M700 in my boat could not actually pick up the 10Mhz time broadcast.

This is a totally scientific construction using the distance between the front cabin door handle and the door handle on the rear head ( about 4m ) I wrapped the wire. the longest piece went 6 times. The shortest 1/4 and there was a length for each 1/4 length. A total of 24 pieces.

They were soldered to a piece of 2m of 12gauge stranded.

I cable tied the bundle together at ~300mm distances.

I then spread the bundle in the aft lazurette and hooked it up.

--

Of course anything is better than nothing.

But on first power-up I got the Maritime Service net on 14.3 Mhz. loud and clear.
Picking up Florida to my marina.

What this proves... something is better than nothing..

Mub

[Santanasailor]

Not rocket science. I couldn't read all the threads to this link as there were too many so if someone has already posted this then forget it. This will work . My sailing guru has been using this method for years and here is his email from the thread. He's a badass, met him in Marquesas and again in Tahiti and beyond.


Ok you will need one hundred and thirty five feet of 18 gauge marine grade wire​ ​.
​ Two of 12 feet, two of 15 feet 6 inches, two of 5 feet 8 inches, two of 33 feet 8 inches.
​ Bundle it together, best in two separate major bundles, one of each length in each bundle, tape them or put them inside PVC pipe if easier, take all the wires and strip and inch of one end of each bundle and twist the whole lot together, solder them into a lug terminal which fits your automatic antenna tuner. Then lay the bundles out as straight as you can passing them through bulkheads etc, but ALWAYS above water level. Max permissible below the water level is about 4 inches, so it is best under the deck. The formula for calculating this is 240 divided by the number of Megahertz which approximates to a band center.​This gives the actual wavelengths in feet to which a wire must be cut or you use half wave length or quarter wave lengths if the whole thing is way to long for practical use.
​ ​