[TowerTalk] Feeding a Delta Loop

[Jim Lee]

Must be some QRM on this message exchange !  You 
specifically mentioned that the bottom leg of your 
Delta Loop was SEPARATED with an insulator -- i.e. 
the loop was not continuous.  What am I missing 
here ?

73

K5KKV

----- Original Message ----- 
From: "Kenneth R. Goodwin, Jr." 
<krgoodwin at comcast.net>
To: <towertalk at contesting.com>
Sent: Wednesday, February 03, 2010 9:25 PM
Subject: Re: [TowerTalk] Feeding a Delta Loop


>
> I went for horizontal polarization with the feed 
> point at the apex at
> the top of the 80 foot tower.  I used a 
> quarter-wavelength RG-11 line
> as an impedance match for the 100 ohm antenna 
> feed impedance to 52
> ohm RG-8 coax to the station.  My baseline 
> reference is the W1FB and
> W1SE article in the October 1984 issue of QST 
> (page 24) which details
> all possible configurations.  When I lost a few 
> of my pine trees that
> support the base leg to pine bark beetles this 
> past summer, I had to
> move the end supports. I was surprised as to the 
> sensitivity of the
> SWR to lengths of the three legs.  Not having 
> all three legs
> reasonably equal caused a significant difference 
> in the SWR.  Guess I
> was lucky the first time I put it up 20 years 
> ago so on the new
> configuration I constrained the insulator 
> connections to the base leg
> with wire rope clips.  Over the years, I've 
> ended up preferring
> insulated wire over bare copper wire - just 
> lasts much longer in the
> high humidity environment.  For K5KKV's benefit, 
> the overall length
> of the delta loop is 1005 divided by f in MHz 
> which makes it a full
> wavelength.  For 80 meters that would three legs 
> around 95 feet each
> or a total of 285 feet/86 meters.  Ken K5RG
>
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