[TenTec] The OCFD Mystique

k8mp at aol.com k8mp at aol.com
Tue Sep 22 19:13:13 EDT 2015

I can't believe this discussion is still going on.
But, since someone mentioned Mr. Windom I have to ask if anyone has ever used or seen what I call the "Classic" Windom, which I believe was the original Windom design.
I have only ever seen one in use and it was at K4DNX's QTH in Winter Haven, FL, way back in 1964. 
The antenna was an 80 meter half-wave. It was a continuous hunk of wire (no insulators 'cept for the end ones. The feed line was a single wire and it was attached to the antenna 
33% in from one end.
I believe OM Herb told me the antenna had an impedance around 300 ohms.
Fifty-plus years later, I'm still waiting to run across another antenna like that.
Later, Joe

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-----Original Message-----
From: Barry LaZar <k3ndm at comcast.net>
To: Wade Staggs <tvman1954 at gmail.com>; Discussion of Ten-Tec Equipment <tentec at contesting.com>
Sent: Tue, Sep 22, 2015 06:09 PM
Subject: Re: [TenTec] The OCFD Mystique

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<pre style="font-size: 9pt;"><tt>Wade,
     The Windom was invented when tube transmitters were around. The

output stage of most, not all, could handle a fair difference in 
but most could not handle the very high impedances reflected 
by feeding in a
voltage loop. So Windom said I have the answer. I'll 
feed the antenna at a
point that would reflect a reasonable impedance 
regardless of band. THERE
NEVER was a consideration for SWR. The SWR 
issue ONLY came up after coax cable
began to be used widely.

     Next, a Windom type antenna, dipole, and OCFD
are the exact same 
thing. The only difference is the feed. A 132' wire will
have generally 
the same gain regardless of how you feed it. However, the
pattern will 
be skewed a bit showing a bit more gain in one direction feeding
it off 
center. Most Windoms, OCFDs are designed for a 300 Ohm feed point
it necessary to use a 6:1 balun transformer. And if you have RF in the

shack, you are not using a good balun or have coupled energy from the

antenna to the transmission line, not an uncommon issue if you do not 
away from the antenna at a right angles.

     I do not intend to flame you so
take off the fire retardant clothes. 
However, I will say you have fallen
victim to a lack of understanding of 
antennas. I really don't mean to
criticize, but more than half of the 
hams today really don't understand the
very basics of antenna design.

     Now having gone through all of that, let
me say, A very good antenna 
is a center fed 1/2 wave on 80 meters fed with
open wire, if you have a 
fair run. Where you enter the house/shack, you
transition to something 
like LMR-400 using a good 4:1 current balun. This
antenna will work all 
of the bands 80-10 with a tuner. The losses will be very
low, even on 10 
meter. You are correct about losses, keep'em down.

why do I use a Carolina Windom type antenna. Because I bought 
into having the
ability to do some fill in at the lower angles on the 
lower bands. The center
fed dipole would have been a bit simpler, but I 
felt at the time this would be
better; mine is a modified Carolina 
Windon that I built using EZNEC modeling.
I have a really good choke 15 
feet below the feed, so I have no problems with
RF in the shack. My 
tuners seem to have no problem with tuning on 40-10; I do
have a little 
trouble on 80 as my antenna is only 66' vice 132' long.

My advice is to just pick a design and put it up as high as you can. 
Let your
tuner do all of the worrying for you. Feed the antenna with the 
least loss
transmission line you can find or afford that fits your 
chosen design, and
then use the heck out of it. Most of this makes 
little difference from a
practical perspective, yet it's more than a 
semester for the engineering
student. Just remember the ionosphere will 
mess with your signal in the 10s of
dbs while antennas may only amount 
to a


------ Original Message ------
From: "Wade
Staggs" <<a href="mailto:tvman1954 at gmail.com">tvman1954 at gmail.com</a>>
To: "Barry LaZar" <<a href="mailto:k3ndm at comcast.net">k3ndm at comcast.net</a>>;
"Discussion of Ten-Tec Equipment" 
<<a href="mailto:tentec at contesting.com">tentec at contesting.com</a>>
Sent: 9/22/2015
4:49:14 PM
Subject: Re: [TenTec] The OCFD Mystique

>Once again I walk
forward with my Asbestos Suit on hi .. hi .. In the 
>QST Article linked below,
modeled on a 66 foot dipole. The SWR and Loss 
>Figures comparing Ladder Line (
Windowed Line ) and Coax is Drastically 
>Different. I know that the Antennas
are different Beasts in many ways. 
>And also that the SWR Figures should be
lower on an OCF Antenna. We are 
>also very aware that Ladder Line can't be
used on an OCF Antenna 
>because it is an Unbalanced Antenna. But .... if you
are going to need 
>a Tuner anyway to cover the Full Bands? Why do folks even
bother with 
>OCF Antennas? Just take a quick look at the Gain an 130 foot
dipole has 
>on 20 Meters using Ladder Line. Sure there are lots of Major and
>Lobes, but the gain in the Major Lobes is Outstanding. Plus you can run

>QRO without having enough RF in the Shack to cause major problems. Hey

>guys, just asking here. There are many people here that are Much 
than me. You never learn unless you ask the questions.... 
>Someday when we can
afford a Faraday Cage.... I would like to play with 
>OCF Antennas again .. hi
... hi ..

><a href="http://www.arrl.org/files/file/Technology/tis/info/pdf/QST_Dec_1993_p70-71.pdf" target="_blank">http://www.arrl.org/files/file/Technology/tis/info/pdf/QST_Dec_1993_p70-71.pdf</a>
So ... we sit here with the 1% Silvadene Cream and Asbestos 
>Underwear on.
Please, be kind fellas This is an honest question because 
>I want to learn
>                                73 from Wade/KJ4WS
>On Tue, Sep
22, 2015 at 12:35 PM, Barry LaZar <<a href="mailto:k3ndm at comcast.net">k3ndm at comcast.net</a>> 
There is nothing magic about an OCFD. It just a variant of the 
>>Windom that
was invented, I believe, in the 1920's. It's nothing more 
>>than a dipole fed
off center so that when you use it on even multiples 
>>of a 1/2 wave the
impedance is either 50 Ohms or in the region of what 
>>your tuner can handle.
If you can get it up 35 or more feet, it does 
>>make for a pretty good all
around antenna. I have a variant called a 
>>Carolina Windom. It's up about 40
feet and I've worked DXCC, mixed CW, 
>>and phone. I've also gotten my WAS
using it and 100 Watts.
>>     The issue of SWR is a red herring. So long
as you can tune the 
>>"system" such that your rig can accept what the tuner
gives it, that 
>>is really all that matters. Yes, there are losses associated
with high 
>>SWR, but if you use low loss transmission line, the additional
>>due to high SWR can be pretty trivial, a 1db or so, depending on SWR

>>and band being worked. On 10 meters my system losses total around 2 db

>>which includes everything behind the tuner.
>>     One thing that must
be remembered is that the transmission line 
>>from the antenna to the station
can be an impedance transformer if the 
>>SWR is greater than 1:1. What this
means is that what you measure at 
>>the station may not be reflective of what
the antenna is reflecting. 
>>So, some of the comments about this antenna works
well over all but 
>>this band or another may not be accurate unless the
effects of the 
>>length of the transmission line is included.
Bottom line from here is put up 66' or 132' of wire. Feed it ~ 1/3 
>>of the
way from an end. Use a 4:1 current balun if you don't want the 
>>feed line to
radiate or voltage balun if you do. And, if you force the 
>>feed line to
radiate, put a good RF choke about 15 or so feet down 
>>from the antenna feed
point point, load it up, and start working the 
>>world. Just remember to use a
good low loss coax like Belden 9913 or 
>>Times Wire
>><a href="mailto:TenTec at contesting.com">TenTec at contesting.com</a>
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one day at a time with Jesus as my Savior. But, still having

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