Bill,
Hopefully I can briefly clarify a few things....
1) Counterpoise vs. ground plane???
Quote:
Originally Posted by Bill_E
This is an interesting discussion but brings up a few questions of my own. First, is there a technical difference between the terms counterpoise and ground plane? Maybe I should look them up in more detail.
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Contrary to what some think, they are not buzz words used by pretentious a**holes....
But, rather
are words which have meaning...
Most "professionals" do not like the word "counterpoise".....but this is how I learned ~ 40 years ago....so while it might make some PhD's cringe, I know that when I use it, I mean the generic ground / artificial ground of an antenna system...whether the dirt/soil, the sea
water, copper wire radials, lead keels and metal
tanks, etc....
And, when I use the term ground plane, I'm almost always referring to tuned/resonant radials....
Please note that these are NOT the engineering-accepted definitions, but when dealing with the real-world of antenna construction, it helps to use definitions that are easily delineated...
Regardless of what you call things, follow some simple rules and things will work fine!!!!
2) RF Grounds, Counterpoises, Ground Planes, Radials, etc.....only things more controversial on-board are anchors!!!
Seriously though, there is some GOOD news here for you!!!
Quote:
Originally Posted by Bill_E
On a practical note. My SSB is fairly old. I purchased it used over 5 years ago. When we installed it we put the tuner in the starboard Lazarette, close to the insulated backstay. Then we epoxied about 6-8 sq ft of copper foil to the hull under the lazarette. This is connected to the tuner with 3-4 ft of heavy copper wire. (I'm not sure of the gauge.) We also kludged a connection to the rudder post with about 8 ft of the copper foil. That rudder post connection has eroded but I don't see a significant difference in performance. I will want to improve the ground before I upgrade my SSB. I am sure that I'd do better with something like 1 inch braid connecting the copper sheet (ground) to the tuner. Should I use braid and redo the connection to the rudder post? Also, a couple of years ago when I hauled the boat, I realized that I have a pair of dynaplates on the top of the keel. As far as I can tell nothing is connected to them, though there may be some indirect connections through keel bolts that I don't know about. Should I use the dynaplates as part of the SSB ground? It would mean running about 10-12 ft of copper braid through the engine compartment to the bilge connection to the dynaplates. Or are they best used as a DC ground and should I work on that?
It may be relevant that my zincs seem to last for a very long time, like 2-3 years so I assume that the AC and DC grounding is pretty good.
This may have raised some questions that are answered elsewhere in the forum so I'll have to do some more checking in the next day or so.
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a) Your set-up sounds pretty good....(see details below)
b) Do NOT use "braid", as this will deteriorate very quickly...even tinned-copper braid is a poor choice for RF grounding....
Copper strap is what is recommended, or even a heavy gauge copper wire (if the run is short), but do NOT use braiding!!!
Also, the thin "copper foil" that is
sold by many marine chandleries, is crap!!!
It is thin and weak....and won't last....
Use copper strapping....and
paint it this some clear lacquer (or any good paint/epoxy), before installing it and it will last a LONG time....(remove the paint/epoxy from the connection points, using sandpaper or Scotchbrite or wire brush, etc....)
Use Pentrox-A as a "conductive grease" to seal/weather-proof the connections as well as provide an excellent "dis-similar-metal-to-metal-connection"....(I've been using this stuff for 30+ years!!)
c) If you have two Dynaplates already installed, use 'em!!!
No question that having them closer to your tuner would be better, but a 10' - 12' run of 3" wide copper strapping (at least 0.012" thick) will cost you about $25 - $35, and will work well...
{I', assuming these are large Dynaplates for your RF grounding, and not the smaller 3" x 6" "ground shoes" for your
lightning ground???}
d) Attaching a short and wide copper strap, from your tuner's grd connection, to an underwater metal (Dynaplate,
bronze thru-hulls, etc.) is almost always going to provide you with an excellent wide-band "counterpoise" (the sea water), that will outperform almost anything else you can install on-board...
But, I do not know if your rudder post provides this direct sea
water connection or not....nor how this connection to the rudder post was done (as the rudder post does need to move/turn), so I cannot know if this would be an effective way to gain access to the sea water....
e) It appears that your AC and DC grounds are fine...don't mess with them...
f) If your existing Dynaplates are the larger ones, it's doubtful they're tied into your DC ground system.....but if they are OR if the are the smaller "ground shoes", you can still use them as part of your HF antenna system ground/counterpoise....you may wish to add some DC-blocking caps (three or four .1uf or even .01uf caps across a small gap of strap, allows good RF grounding, but blocks DC...)
3) Sorry to be so brief....but I've wriiten so much about RF grounds and counterpoises lately, I'm a bit burned-out!!!
Have a look at the SSCA Disc Boards for a LOT more info/details!!!
http://www.ssca.org/forum/viewforum.php?f=5&sid=2abd6ce02807c9b0a6fa8641aae1 4940
Especially here....
http://www.ssca.org/forum/viewtopic.php?f=5&t=13490&start=75
http://www.ssca.org/forum/viewtopic.php?f=5&t=13490
Fair winds...
John
s/v Annie Laurie