[TenTec] Tuner

[Rick - DJ0IP / NJ0IP]

James, Jim is correct in EVERY point.
Explaining all of that goes beyond the scope of an email or two.
I'll send you several online links where you can read up on this.

The only place I take exception with what Jim wrote is, I would not call the
OCFD (or Windom) a bad antenna.
There are circumstances where it is the best possible antenna.

Jim, you wrote "look at my lot".  I've seen it before.  Outstanding!  Well
done.  But you're lucky your neighbors didn't shoot you (hi).
"My" is the key word in your strategy there.
Here in Europe, most people rent and can't do as they wish on the grounds
where they live.

Example:  My current QTH.  The landlord permitted me ONE single antenna.  It
must be as inconspicuous as possible.  Normally under these limitations, I
would run an openwire fed antenna.  Running openwire through the air at this
QTH is absolutely out of the question.  Yet I want to run contests on 6
bands.

My OCFD works 5 of the 6 contest bands, without a matchbox.
It is on a single fiberglass pole (which I have promised to paint green to
blend in with the trees).
It uses thinner wire than I would like, but that helps make it invisible.  
The coax runs along the ground, out of site.  Once I get the pole painted,
it will be invisible.

With this antenna, I scored over 1 million points in CQWW CW last year.
What other invisible antenna enables you to do that?
It's horses for courses.  

Why did I move here?  Because my XYL chose the place and signed the lease
while I was still in the states.  She said "honey it's beautiful and the
landlord says you can put up an antenna".  So I told her to take it.  Turns
out "beautiful" to the XYL means the garden is beautiful with lots of place
for her flowers.
We live on a mountain side with a 40 degree incline.  TERRIBLE for a ham.
But until I move, I must make the best of it and I found OCFD to be the best
there is under these condx.

I'll gladly try anything else, but it has to be nearly invisible and work
all bands.

BTW, I limit myself to 500w and besides having a dual-core Guanella at the
feedpoint, I break up the feedline with 3 additional RF chokes on its way to
the shack.  Learned that from K9YC! (hi)   My chokes are currently Maxwells
but I'm in process of replacing them with coax looped through multiple
chunks of ferrite (as per GM3SEK).

73
Rick, DJ0IP


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Richards
Sent: Tuesday, July 09, 2013 8:45 AM
To: k9yc at arrl.net; Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Tuner

Really?   Please explain.

I ask because Rick DJ0IP and I have both spent considerable time researching
and building various OCF dipoles to build multiple-band antennas which do
not depend (or which depend less) on a tuner or matchbox than other designs
(e.g., a G5RV).

While I have yet to discover the Holy Grail of multi band antennas, the
articles I read do not mention the limitations your cite.  I am not arguing
with you - I am just curious to know more, mindful of the paucity of other
references thereto.

I took care to employ a substantial, heavy duty 4:1 balun specifically
designed for the precise feed point offset I used - which is at the 25/75%
position, and not at the usual 33/67% position - and this provides very low
SWR on 40m and 20m and also allows operation on 15 meters, which is usually
not possible with traditional OCF designs.  My research and measurements
indicate feed point impedance is approx 200 ohms, substantially lower than
the usual 300 ohm figure typically realized at the traditional 23/67%
offset.

The balun was designed to both transform impedance and block feed line
radiation as a choke to minimize feed line radiation - not because I thought
there would be more than a typical dipole, but just in case.

Thus, I ask for an additional gloss on your comment, because I cannot
imagine how or why one would expect an OCF dipole to exhibit more feed 
radiation than it always has.   That is a curious concept.  I also 
cannot imagine it would be more susceptible to common mode noise than a
regular coax-fed dipole.  Ergo, pray tell more.

Thanks!
------------------- K8JHR  --------------------


On 7/9/2013 2:21 AM, Jim Brown wrote:

> MANY years ago, when the world was much quieter, and when homes were 
> not full of entertainment equipment with Pin One Problems, OCF 
> antennas were a very good idea.  That was then, and now is now. And 
> NOW they are a BAD idea.
>
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