Richard Clark wrote:
On Thu, 15 Mar 2007 15:57:50 -0400, Michael Coslo
wrote:

On Thu, 08 Mar 2007 08:03:56 -0800, Richard Clark
wrote:
Coming in late, did I miss someone's extravagant claim that a OCF
could do better?

The idea that an OCF is superior to a dipole, and certainly Richard's
statements would indicate that; makes me wonder why everyone isn't using
them!

Hi Mike,

With all the intervening comments removed, want to reconsider that
again?

An OCF is simply resonant at exactly (by modeling) the same points as
the dipole of the same length. Resonance resides in the wire, not the
drive point. Of Course, F***! (expletive deleted to explain the
meaning of OCF) as the drivepoint is moved through the length, its
fundamental Z (still real) varies from low (at midpoint) to high (near
endpoint) in much the same manner as we would expect for the
difference between a conventional halfwave dipole and conventional
halfwave end-fed. The harmonic drivepoint Zs follow their own
sinusoidal roller coaster through the shift in feed point.


Sorry for the delay in response Richard, but as a confessed not-so-wise
guy, I've gone back to modeling to see exactly where I've erred and to
discover the source of my density.

And darned if I can't figure it out!

I've modeled Both OCF and frequency cut dipoles, and darned if the
frequency cut dipoles don't look better.

Your argument makes it sound as if the OCF has identical performance at
those same points as a frequency cut dipole. Resonance or not, there are
bands for which I still need a tuner, which makes the whole purpose a
little moot. The SWR curve of the OCF really doesn't look all that hot,
sometimes it is just passable at the frequencies of interest,and looks
better off frequency. and it looks like something a radio with a *good*
autotuner could take care of. That has been my experience with them.
Sure seems like a compromise to me. YMMV.

- 73 de Mike KB3EIA -