Re: OT: Need Antenna Tuning Help

Posted by Jim Bennett on Mar 08, 2012; 5:06pm
URL: http://elecraft.85.s1.nabble.com/OT-Need-Antenna-Tuning-Help-tp7327188p7355572.html

The feed point is at exactly the same elevation as the FCP - just around five feet off the ground. The FCP should have been eight feet high, but that would put it in the neighbor's cross-hairs and we live in a CC&R / HOA area, so stealth is best for me. The isolation transformer unit is loosely strapped (in it's box, of course) to the side of a redwood tree, about three feet horizontally from the FCP, which is a few inches off of the wooden property line fence. When I built the FCP, I left several feet of extra #12 AWG copper wire at the bottom end for connection to the FCP. It is that wire that runs over to one binding post on the isolation transformer. The other binding post connects to the vertical part of the Inverted L, which runs up through the limbs of the tree, approximately 31 feet, and then around 40 feet or so horizontal across the back yard. It is not perfectly horizontal - comes down on a slight angle. The antenna wire I used is #13 AWG "Silky Coat" from The Wire
 man.

The transformer is a true isolation transformer - 15 bifilar turns of #14 AWG Polyimide Insulated Wire with teflon sleeving, wound on an AmidonT300A-2 powdered iron toroid. All part numbers, pictures, and a complete description can be found at: http://www.w0uce.net/K2AVantennas.html

This is really cool for me, as I'm waiting for that elusive KAT500, but I can now freely roam around the CW part of 80 meters and the KPA500 happily follows me!

Jim / W6JHB

On   Thursday, Mar 8, 2012, at  Thursday, 8:34 AM, WILLIS COOKE wrote:

> Congratulations Jim!  I have been watching this thread with interest to see how it worked out.  I would like to know a bit more.  Is your feed point at the same elevation as your counterpoise, or at ground level?  If at ground level, describe your transition to five feet for the counterpoise.  What do you use for a support and how high is your transition to horizontal?  Is your transformer a true isolation transformer with two windings and DC isolation or an UnUn wound transformer?  Is your powdered iron core a rod or toroid?  What is the Amidon model number?
>
> Again, congratulations!  I love this kind of dialog! 73!
>  Willis 'Cookie' Cooke
>

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