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Message |
    
Supertech1
New member
Username: Supertech1
Post Number: 7
Registered: 1-2005
| | Posted on Thursday, January 20, 2005 - 1:02 am: | 
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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. |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 156
Registered: 9-2004
| | Posted on Thursday, January 20, 2005 - 9:15 pm: |
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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!!! |
Tech833
Moderator
Username: Tech833
Post Number: 960
Registered: 8-2002
| | Posted on Friday, January 21, 2005 - 7:50 pm: |
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And they are more broadband than a thin wire. |
Hdluvbugs
New member
Username: Hdluvbugs
Post Number: 5
Registered: 12-2004
| | Posted on Friday, January 21, 2005 - 8:03 pm: |
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supertech1 ?? can you give me more info on this ant.?? like lenth -ground? |
Mikefromms
Intermediate Member
Username: Mikefromms
Post Number: 376
Registered: 6-2003
| | Posted on Saturday, January 22, 2005 - 10:50 am: |
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I built a copper tubing dipole. Works great. Just don't have anyplace to put it up.
mikefromms |
Patzerozero
Intermediate Member
Username: Patzerozero
Post Number: 347
Registered: 7-2004
| | Posted on Sunday, January 23, 2005 - 9:24 pm: |
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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. |
Supertech1
Junior Member
Username: Supertech1
Post Number: 14
Registered: 1-2005
| | Posted on Friday, January 28, 2005 - 12:20 am: |
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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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