My son is a recent ham, and he uses an Alpha Delta OCF dipole (135').
If you want to see the R+jX measurements of this antenna at about 45',
go to www.telepostinc.com/lp100.html and scroll down to the middle of
the page. I show graphs of the antenna as measured by my HP-87510A VNA,
AEA CIA analyzer, Autek VA1 and my LP-100 Digital Vector Wattmeter.
It's a surprisingly good looking set of impedance curves, and the
antenna performs quite well for my son who only uses 10W with an
Elecraft K2. The K2 is able to match it on all bands with the built-in
tuner.
73,
Larry N8LP
Eugene Hertz wrote:
> Hello all,
>
> I am thinking of abandoning an original idea for a fan inverted-L and instead
> going for a windom/ocfd. I saw a few mfg of these for up to 80m and while
> they both had very similar total length, the length of the legs were rather
> different:
>
> Buckmaster 7-band OCF: 45' + 90' = 135' total (claim: 75/80, 40, 20, 17, 12,
> 10, & 6 meters)
>
> Carolina Windom OCF: 50' + 83' - 133' total (claim 80-10m)
> Others ocf mfg's have similar length legs.
>
> Another point of confusion for me. The buckmaster does not have a predefined
> vertical component. You add your own coax and they say the length is not
> critical. The carolina (and others) have a specific 22' vertical radiator
> and then you add your own coax after a "line isolator"
>
> Would anyone be willing to help me unravel these mysteries?
> First: What is the effect of the different leg lengths?
> Second: What is the impact of having/not having a specific length radiator vs
> just add coax.
>
>
>
>
>
>
> _______________________________________________
>
>
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>
>
>
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