[TowerTalk] Ferrite Balun on a LPDA?

[Steve Katz]

I have a Tennadyne LPDA and have never tried the ferrite balun; however when
servicing the antenna after it was up 4+ years I decided to replace the big,
heavy & ugly RG213/U choke balun with one made of thinner, lighter weight
cable that would also look nicer and not unbalance the antenna.  I chose to
use RG400/U PTFE coax (only .200" diameter) instead.  It's thinner, lighter
and prettier than the .405" OD black RG213/U and easily handles 2kW.  I
splice it to the main feedline to the shack using ordinary UHF connectors
and a UHF barrel PL-258 at the boom-to-mast clamp area, so the heavier coax
makes the rotator loop and goes down the tower. You might consider something
like this....

-WB2WIK/6

-----Original Message-----
From: Clint Talmadge [mailto:unclebudd at bellsouth.net] 
Sent: Thursday, June 14, 2007 10:00 AM
To: towertalk at contesting.com
Subject: [TowerTalk] Ferrite Balun on a LPDA?

I am close to putting my Tennadyne T-6 back up. When I took it down it had
the prescribed Coax Balun on it and it showed it's age. For the last month
or so I have had the antenna on a short perch in the yard with a Ferrite
Bead Balun on it and it sweeps fine using an analyzer and I have even made a
few DX contacts on it. The balun I am using is a W2AU by Unadilla. I have
searched different archives and the only one with any significant
information is one I started on eHam some years ago.The old Tennadyne maker
specifically said he had not tested a ferrite balun and did not recommend
them. The reasons I would like to use the Ferrite Balun are:

Lower profile - less wind resistance
Longer life - better built than my taped Coax Balun
Better Balance - the antenna is much closer to being balanced (weight wise)
with the Ferrite Balun

There is precious little written about feeding LPDAs. What little I have
read does not address this.

I am open to suggestions as the antenna will not go up till some time in
early July.

Clint - W5CPT

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