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Supertech1
New member
Username: Supertech1

Post Number: 7
Registered: 1-2005
Posted on Thursday, January 20, 2005 - 1:02 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I use a cone mount on top of my truck w/ a frances amazer 8' whip. but when I go to the hilltop, I like to blow off 2kw sooo....I made a 3/4" all copper pole(pipe) trimmed with a pipe cutter until it match in at 1.1/1 then caped it off. This all copper 3/4" dia.-1/4 wave whip cannot mobile around for obvious reasons and I know it has been done before.
But, MY GOSH!! IT REALLY KICKS BUTT!!! 'Just thought it was worth mentioning here.:-)
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Kid_vicious
Intermediate Member
Username: Kid_vicious

Post Number: 156
Registered: 9-2004
Posted on Thursday, January 20, 2005 - 9:15 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

you are experiencing the benefits of "skin effect". this is a propety of RF that means the signal runs along the outer diameter of the antenna element. not so much down the center. so a 3/4" pipe will outperform a copper wire. plus, they can handle serious wattage!!!
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Tech833
Moderator
Username: Tech833

Post Number: 960
Registered: 8-2002
Posted on Friday, January 21, 2005 - 7:50 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

And they are more broadband than a thin wire.
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Hdluvbugs
New member
Username: Hdluvbugs

Post Number: 5
Registered: 12-2004
Posted on Friday, January 21, 2005 - 8:03 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

supertech1 ?? can you give me more info on this ant.?? like lenth -ground?
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Mikefromms
Intermediate Member
Username: Mikefromms

Post Number: 376
Registered: 6-2003
Posted on Saturday, January 22, 2005 - 10:50 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I built a copper tubing dipole. Works great. Just don't have anyplace to put it up.

mikefromms
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Patzerozero
Intermediate Member
Username: Patzerozero

Post Number: 347
Registered: 7-2004
Posted on Sunday, January 23, 2005 - 9:24 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

st1's coppertube is sorta how the LARGE open air coil skip talking antennas came about. the coil shortens it so you can drive around with it. skin effect/capture area is the theoretical advantage of those BIG antennas. that, and the ability to handle large amounts of power. we made an antenna out of 3" copper pipe with a funky matching system we got out of a quad antenna handbook from the early 70's & used it on a late 60's chevy dumptruck with a VERY VERY EARLY multiple transistor mobile amp that did over 1000watts on a heathkit wattmeter and a 23ch pace ssb mobile,back around 78 or so.
match was good, antenna was too big to drive around with though, francis whips would last for a few days before swr's go to infinity. coming down a hill towing a landscape trailer & steering rag joint let go. resulting fire incinerated pace. don't know who ever ended up with amp.
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Supertech1
Junior Member
Username: Supertech1

Post Number: 14
Registered: 1-2005
Posted on Friday, January 28, 2005 - 12:20 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hdluvbugs,
My all copper antenna tuned in at 105" measured from the top of the 'pineapple cone' mount to the top of the soldered on copper cap. The pipe is 3/4" dia. thin wall(red) copper. On the bottom, I used a 3/4" to 1/2" reducer with a 3/8" copper bushing inserted into the 1/2" end to center the 3/8" mounting screw and nut before soaking the whole thing with silver solder(be carefull not to get solder in the threads) I used a zinc plated nut and bolt.
I would suggest you start with 108" copper pipe and trim 1/4" to 1/2" off at a time with a pipe cutter until it matches in. If you cut off too much, you can solder the copper cap on a little high on the pole by using a 1/4" to 1/2' left over piece inserted into the cap--as a shim.

All cars and trucks have a different 'ground footprint' depending on size and antenna placement and so final lengths can vary slightly.

Also, for safety, I must warn you NOT to attempt to drive around with this antenna because if it ever came off, it could turn into a lethal harpoon and you wouldn't want to impale anyone!! Would you?:-) --Not to mention it WILL tweak the heck out of your mounting location. If you 'side' mounted it and supported it properly with an insulated standoff at least 1/3 up from mount and used heavy wall 'blue' copper maybe it would work for driving around but I personally know that 'top, dead center' is the best way to go for all out performance.

Good luck and always remember..

TUNE FOR MAXIMUM SMOKE:-)

ST

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