There is a whole sub-culture of people working with OCF's. There is a Yahoo
group. There is a rather nice website by Serge Stroobrandt, ON4AA, with links
to a lot of the literature and his own design: http://hamwaves.com/cl-ocfd/
Among other things, they recommend two baluns at the feed point, a hefty 4:1
followed by a choke balun, and maybe another choke balun down the feed line a
ways.
I've been tempted to try an OCF because the trees are in exactly the right
places but I'm hesitant because the last time I tried an OCF I had the sort of
fun Jim alluded to. It was a devil trying to find that 200 ohm point. The feed
line radiation gave me RFI in every device in the house. Of course, back then I
was using one balun, not two, not three.
Life sure is easier with (more or less) balanced antennas.
Jon, K6JEK
On Jul 9, 2013, at 12:36 PM, Jim Brown wrote:
> On 7/9/2013 12:57 AM, Rick - DJ0IP / NJ0IP wrote:
>> 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.
>
> Yes, that's the unfortunate situation that many hams are stuck with, and so
> was I for 30 years until I bought that house in Chicago. At a rental
> apartment, I had a Butternut vertical at the edge of a roof, and very low
> visibility wire dipoles strong across the roof and from the roof to a
> telephone/power pole in the alley (that the telco lineman would remove when
> he saw it).
>
>> With this antenna, I scored over 1 million points in CQWW CW last year.
>> What other invisible antenna enables you to do that?
>
> You were only able to do that because you are in EU. It is 20 times more
> difficult to do that from W6, and even more so from places like VK/ZL.
>
>> It's horses for courses.
>
> Of course -- that's the approach ALL of us should be taking for antennas. I
> often help local hams figure out how to make the best use of their small lots
> for antennas. N6NUL and W6SX are two guys who have done a LOT with not much
> space. N6NUL has a town house near the Santa Cruz harbor, with a TINY yard.
>
>> We live on a mountain side with a 40 degree incline. TERRIBLE for a ham.
>
> You should see NI6T's QTH, about 20 miles from me. He's at the bottom of a
> VERY deep canyon, with the mountainside rising at least 800 ft above him on
> both sides. His antennas are up 60-80 ft, but are more than 300 ft below the
> major highway that weaves its way around the rim of the canyon. And like me,
> he's surrounded by giant redwoods, and uses them to support his antennas.
> Garry is on the DXCC Honor Roll. Like you, his XYL chose the house, and
> although he has been a ham since his Junior High School days, he was not
> active when they moved there about 30 years ago. :)
>
> 73, Jim K9YC
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