Spencer,
That antenna is a good antenna but I think you will find your auto tuner
will not match it on 80m.
They don't like low impedance loads at all. And they are very inefficient
at low impedances.
You didn't specify what kind of balun you intend to build. You said dual
core choke balun. Did you mean 1:1 or 4:1?
The best solution would be a 1:1 Guanella for 40 and 30m and a 1:4 Guanella
on 80m. Basically what you want to do is take the normal 4:1 and turn it
around backwards, so that the side with 50 Ohms is to the antenna and the
side with 200 Ohms is to the matchbox. That will help transform the roughly
5 Ohm load up to 20 Ohms which might possible bring it in range of your
matchbox.
You can actually build one balun with two cores and make it switchable so
that you can switch back and forth between 1:4 and 1:1. For 1:1 simply
parallel both ends of the balun's 2 transmission lines; for 1:4 connect the
antenna side of the balun's transmission lines in parallel and the matchbox
side in series.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Spencer
Sent: Wednesday, December 31, 2014 6:28 PM
To: tentec@contesting.com
Subject: [TenTec] antenna help
I made one of these. used a relay at the feed point to switch phase between
the loops. My next will use a dual core choke balun with a auto tuner and
relay at the feed point.
http://davekalahar.com/Misc_Files/ARRL%200802%2080%20Meter%20Loop.pdf
HAPPY NEW YEAR
Spencer W1GAK
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