[amsat-bb] Re: Helix matching

Edward R Cole kl7uw at acsalaska.net
Fri Sep 27 23:27:58 PDT 2013

Making these matching sections is not as critical 
as many made them out.  Here is a 1420-MHz dish 
feed helix I built years ago.  I used the same 
technique for the 2.4 GHz helix feed I used for AO-40.

73, Ed - KL7UW
Joe: note the KLM-11 el yagi made from a KLM-22C I got from you years ago:
scroll down to set of three photos.  The KLM-11 
is mounted just below the tribander

At 03:05 PM 9/27/2013, Joe Fitzgerald wrote:
>On 9/27/2013 8:57 AM, Robert Bruninga wrote:
>>Why don’t we see simple ¼ wave 75 ohm lines used as a first step in
>>matching a 140 Ohm Helix to 50 ohms?
>In my limited experience, it's easier to diddle 
>around with a strip of brass or copper at the feed end of the Helix..
>For example:
>I remember building a 1/4 wave coaxial matching 
>section out of a piece of copper pipe with brass 
>rod down the center.    I think it was from a 
>design in the ARRL antenna book as published in 
>the late '70's.   It was a pain to build since I 
>had to sand down the brass rod to get it to the 
>right diameter, and I was never really sure how 
>well it worked, since I did not have any antenna instrumentation at the time.
>-Joe KM1P
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73, Ed - KL7UW
dubususa at gmail.com
"Kits made by KL7UW" 

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