I am using a 230 ft horizontal loop up about 30 ft fed with 600 ohm homebrew
ladder line.
I have a revamped johnson matchbox, a TT 238A tuner and am currently running
a Palstar BT1500A balanced L antenna tuner.
All 3 had about the same field strength from 80 thru 30 meters. From 20
meters thru 10 meters The Palstar and TT has about the same field strength
readings with the matchbox showing less rf field strength.
Both the Palstar and 238A are far easier to tune (lower Q I assume) than the
matchbox.
The matchbox and Palstar show the best balance with the 238A with its
internal 4 to 1 balun showing a bit of feeder imbalance especially on 10
meters.
I used a field strength meter almost directly underneath one leg of my loop
to determing readings for field strength and used the same meter taking
readings equadistant...about an inch or so...on either side of the feeders
to determine balance criteria.
I suspect the 4 to 1 balun in the 238A tuner simply isnt up to snuff as far
as balance is concerned...and I would suspect it's efficiency on anything
above barefoot power.
I havem't made much sence about the matchbox not having much field strength
readings on the higher feqs...any guesses? too small coil wire size perhaps?
----- Original Message -----
From: "Jim WA9YSD" <wa9ysd@yahoo.com>
To: <tentec@contesting.com>
Sent: Monday, July 07, 2008 9:01 PM
Subject: Re: [TenTec] OT: SWR & Coax
I am tying to catch up with my reading. I had a tuner made for open feed
line feeding an 80M folded dipole. I had 2 roller inductors in series with
the feed line. I found that sweet point, balance on the coil and link. I
cannot remember if I had to touch the caps on the coil. If I did, it was
not much.
Now I moved to new QTH not practical for open feed line and bought a tuner
just to tune coax. I am on my 4th coax tuner, its the Tec-Tec 253. "L"
Networks make the most sense to accomplish proper tuning, and very pleased
with it. Its a keeper. I sure miss that old open line tuner. Or should
I?
Keep The Faith, Jim K9TF/WA9YSD
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