Tom,
For 100w, a good commercial 300 Ohm twinline will be sufficient.
You can get this from THE WIREMAN, or RADIO WORKS.
If you are ever going to run an amp, then I would go with the 450 Ohm window
line (same two sources).
In the past I had the opinion that a homebrew ladderline is better and have
often built my own, but it is a lot of work. Unless you just want to do it,
then I wouldn't waste my time.
Last year there was a very good article in QST, testing various types of
open wire.
It was conducted by Joel, W1ZR (aka "The Dr. is in.).
His conclusion was that there was not really a distinguishable difference
between the different openwire types.
However, he did comment that when the weather changes, for instance snow and
ice clings to the openwire, the home brew openwire requires less re-tuning.
This I can vouch for as I have seen it many times.
That's no big deal.
More important (by far) than the type of openwire is, "how you attach it to
the dipole".
If you do not use a physical strain relief, it WILL break.
It's only a matter of time.
The Ladderline with solid conductors breaks sooner than the ones with
stranded conductors, but they all break.
I create a strain relief by trimming the middle part of the ladder line back
a bit, then passing the two leads of the openwire through pre-drilled holes
in the insulator.
Run them with insulation through the holes and then use two UV resistant
(black) Cable Ties for each wire to secure it.
Run the two wires of the dipole through the normal holes of the insulator,
including insulation and secure them.
Then solder the ends of the openwire to the ends of the dipole halves.
There also some commercial center connectors available, but they are big,
bulky, and heavy.
Since I typically use a fiberglass pole, I can't have that.
I build my own center insulator out of plexiglass, about 1/4" thick, 2" long
and 3/8" wide.
Coat the solder joints with liquid electrical tape.
An overall length of 26m is already long enough for good performance on
80-10m.
34m will give you slightly more performance.
Going from 34m to 42m (full size 80m) didn't seem to make much difference.
In a pinch, I've even used 20m overall length and worked 80m "pretty well".
But it is starting to get a bit short for that band. You will notice a
difference by going to 26m.
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of tom stewart
Sent: Sunday, January 09, 2011 12:07 PM
To: tentec@contesting.com
Subject: [TenTec] Suggestions please
I have been off the air for a while and am now trying to get back up to
speed(cw only here). I need to rebuild my antenna and am curious what you
folks recommend for a ladder fed doublet- buy or build. Also I want to
reassess my tuner/balun set up. I know this is a gigantic can of worms and
has been hashed since the beginning.
I use an OMNI VI and only run 100 watts. I do not have plans to install a
power amplifier at this location. I am looking for efficiency and need to
avoid causing interference as my home is close to the neighbors.
Thanks in advance for any suggestions.
Tom Stewart N7ESE
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