SWR and common modes currents are unrelated. You can have a perfect
match, and still have excess current on the coax shield.

Hi Mark, I agree, but those common mode currents can make your swr meter read
strange things.
If one has excess common mode current, the placement of ones swr meter along
the antenna system will effect what it reads. ok ok TLI meter.:-)
73 Gary N4AST

I make a 4:1 transformer out of coax and feed the J-pole at a higher
impedance point, this also gives a better match across the whole band.


"Dr. Slick" wrote in message
om...
(Dr. Slick) wrote in message
. com...


Ok, folks. Went to the local ham radio outlet, and
the dude said that the polyethelene foam RG-8 isn't very good in terms of
breakdown voltage, which is about 600 RMS, i believe.

However, RG-213 is solid polyethelene, with a BV of 3700 volts RMS.

So i went with the RG-213, and reduced the total turns to 4
(originally 6).

Hopefully this will not melt again.


Slick


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Dr. Slick wrote:
"Can I get away without using the tnductive loops?"

A similar "Super-J" is shown in the 19th edition of the "ARRL Antenna
Book" on page 16-25. I see no mention of decoupling the outside of the
coax.

Exterior coiling and exterior coupling of the coax should hardly affect
the interior of the coax.

W2DU ferrite cores could be used for the same purpose as coils in the
coax as could other decouplers such as sleeves, etc.

Melted foam inside the coax might indicate a near short nearby.

Load on the coax should be a resistance of Zo value and if so, there
should be no high-current hot spot.

Best regards, Richard Harrison, KB5WZI