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Parasitic effect is not what is being discussed here. This is direct coupling. I assure you that 4 wraps of this think sheet rubber is more than adequate separation. Parasitic isolation is only accomplished by using a non-conductive mast like plastic pipe.


Well the "mod" is done and there is no difference in my TVI. Have a dozen different torroid and ferrite chokes coming and I'll distribute those around on the TV & radio in the next attack

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If you are using rubber for an R.F. insulator you have achieved DC isolation but not R.F. isolation. Materials don't care about semantics.

What is parasitic isolation? The term doesn't appear in any of my reference books.

If you are talking about adding radials to a "Big Stick" design antenna the current will flow into the properly placed resonant radials without insulating anything. Doc correctly stated this before. Same principal as a fan dipole.

There are a LOT of rubber sheet formulations that contain carbon black and are quite conductive. I'm not saying that was what you used for your insulating of the antenna, but from the time I saw rubber conducting electricity (about 60 amperes' worth over a three-foot length) on board a Navy ship many years ago, I have always double checked!

Same thing goes with just about any "flat black" paint.

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The Imax w/ GPK is up and successful! The TVI is reduced but not eliminated. Signals both ways to all the locals is up 1.0 - 2.5 S units. Good investment for the gain received.

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Supplying All Your Wire and Weasel Needs Since 1869 * All Orders Come With A Free Pack Of Vazomyne For Sustained Performance

good to hear you had positive results on both TX and RX .
can you tell any difference in your noise floor/static levels ?

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Yes absolutely Booty I forgot to mention. Imax is much quieter I noticed that right off the bat. Is a quiet day anyway but meter lays slap on zero and is noticeably quieter noise floor. Nice!

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Supplying All Your Wire and Weasel Needs Since 1869 * All Orders Come With A Free Pack Of Vazomyne For Sustained Performance

getting a stronger recieve level and a lower noise floor is a double shot in the arm for your ears .

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wire weasel,

did you end up using the choke balun?
if you posted whether you did or not, i mustve missed it.

if not, you might try it.

i have heard from a few different sources that four radials are not enough to decouple all of the currents on the coax shield.

whether or not this applies to your particular situation i dont know.
LC

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LC, how do we tell if our choke is working as you suggest? I have heard many claims on the issue, but nothing has ever been suggested that is provable and duplicatable to be obvious and convincing without a doubt. I'm reluctant to take anything I hear on the Internet without being able to duplicate the process and realize some or the same results. Otherwise I have to depend on blind faith, which is so often based on a whole lot of CB BS. I know what efforts I make on testing and it is not easy work. There are exceptions I'm sure, but I suspect that most of the claims we hear are just so much writing on the rest-room walls. Most guys are just not going to put forth the effort necessary. That's alright though, it takes a lot of work, but I say, "...don't give me your ideas and dreams as though they are facts without producing some tangable results."

I am convinced, however, you're correct in your comment about adding extra radials, but I want to try and duplicate my findings on that subject several more times to make sure. I have experimented with such ideas in 2003, 2006, and my recent work on adding radials did not prove to be successful in duplicating my previous efforts, so I must re-think what I am trying to do in each step, plus I do not even try to report my work from memory and this is where even my notes sometimes fail me.

W8JI is a much written author on such matters and in this case says, somewhere on the Internet, that just touching or moving your coax or your radio is not a good enough test for the presence of Common Mode Currents. He says a suitable clamp on amp meter is required to definitively tell if CMC are on the feed line. That said though, I suspect that CMC are present as a matter of degree, and if that degree is small---is that important enough to be concerned about?

I think I recall that freecell once told us that the Sigma 4 responded exceptionally well to the addition of a choke at the feed point. I recently added a choke, 7' section of RG8/U coiled on a 4.5" non-conductive form, and so far I can't tell anything except that my bandwidth curve shows me that my adding the 7' feet of coax dropped my SWR from an average of 1.21 @27.605 down to 1.16 @27.305. At this point this only shows me I have a bit of feed line transformation in my system due to a bit of reactance at resonance and frankly I am not one that thinks that is the least bit important to operastions.

I also may be realizing a bit of reduction to noise from the radio due to the choke, but it is really hard to tell with conditions as they are and because I cannot test the system for noise differences instantly---using a line switch. I am just taking the facts of my choke on faith and that it is working as it should---making some positive difference.

So, you see what I'm saying about following the ideas and claims of others on the Internet. To be fair though, I was not scanning at the feed point so my figures will likely be skewed a bit due to reactance and the approximate 82' feet of feed line I have installed, but I have nothing more to go on than some easy to say words, right?

LC, if you know of a test or comparison procedure to be sure in this case please let me know and I will check it out even if you are just brainstorming and idea.

How say you?

Hey guys,

No I haven't tried the balun but that may be the next step.

Mr. Marconi I believe the point of a balun is use on if you need one. If station is experiencing TVI or other stray RF in the shack or around the house, then taking steps to remove stray RF from the feedline can be one cure and/or one thing to try anyway. These baluns are easily done/undone.

TNX!!

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Supplying All Your Wire and Weasel Needs Since 1869 * All Orders Come With A Free Pack Of Vazomyne For Sustained Performance