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Antenna Rebuild, Some PV Sundancer History

17 Jul

After an awfully long time my new feedline is in place. While I was doing my feedline install I restrung my dipole with AWG 10 105 strand wire as opposed to what I used to use, AWG 22 stranded wire. With very little time on my new antenna system I must say it seems to work well. The primary reason for the update was to insert KW capable chokes into my feedline since the existing ones were designed for only 200 watts. I am pleased to report that they appear to be working fine.

The boxes attached to my mast contain a common mode choke constructed with Mix 43 ferrite and RG-393 teflon coaxial cable. The choke exhibits approximately 2700 ohms of common mode impedance at 14 MHz.

The impedance plot vs. frequency can be seen in the following image.

There are four of these inserted into my feedline. The feedline itself is constructed from 1/8th inch phosphor bronze wire rope and homemade fiberglass spreaders.

Above is my new feedline waiting for epoxy to cure.

The whole project took a lot longer than I thought it would but so far at least it has been very rewarding. Anyone questioning the use of common mode chokes in feedlines should become more aware of the concept of DbW/Hz.

Accounting for all the design requirements necessary due to multi-band operation at high power using a single feedline and antenna has been a very rewarding learning experience. About the only improvements that I can think of at the moment are increasing the size and strength of my mast and perhaps seeking a little more height.

Palos Verdes Sundancers- some background. Years ago a fellow named Hugh Cassidy wrote and edited a publication called the West Coast DX Bulletin. In it he introduced the concept of Sundancers. Folklore and literature are replete with stories of farmers and hunters using strange tactics to conjure up crops or game. In our case, radio aficiandos world wide took to using the Palos Verdes Sundancers to conjure up sun spots-the preferred excitation force for improved propagation. Anytime a new cycle was trying to get started up would pop the Sundancers. Well, the Sundancers have taken early retirement, so promoting the Texas Anole in sufficient numbers to conjure sun spots is my chosen way to replace Sundancers. Preferrably dancing Anoles.

Above is the Texas Anole.

Links to stories about the Palos Verdes Sundancers and more can be found here:

http://www.geocities.com/CapeCanaveral/1641/sundancers.html

More on this topic later.

Thanks for reading, Best Chas W7MAP/5


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Posted by on July 17, 2008 in Radio

 

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