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Re: [TowerTalk] Insulator Placement Clarification

To: "Jim Lux" <>
Subject: Re: [TowerTalk] Insulator Placement Clarification
From: "Jim Brown" <>
Date: Tue, 04 Sep 2007 18:18:40 -0700
List-post: <>
jeremy-ca said:

>They will decouple similarly as when used over coax or small ones
>over transistor leads.

Which is not very much decoupling at HF. I agree with Jim Lux that 
ferrites in this application are a complete waste of money. 

Ferrite chokes are VERY useful as "egg insulators" in transmission 
lines, but again, at HF you need a WOUND choke, not a few beads, to 
be effective. 


As to the application to LPDA or multiband antennas -- what matters 
is the wavelength of the transmit frequency. The key is to make the 
smallest segment of the guy wire a relatively small fraction of a 
wavelength at the highest transmit frequency. I'd go with Frank's 
advice of a quarter wave being the maximum length, and consider 
going even shorter very close to the antenna. 


Jim Brown K9YC


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