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Old March 30th 09, 10:01 PM posted to rec.radio.amateur.antenna
Richard Clark Richard Clark is offline
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First recorded activity by RadioBanter: Jul 2006
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Default solarcon I-max 2000

On Mon, 30 Mar 2009 19:15:04 +0100, "Andy"
wrote:

Thanks all, for your input. I'll stick it up on the mast this weekend and
try it without any ground plain legs to start with. It will look a lot
tidier without legs on and I won't have the problem of having to put up a
longer stub mast to accommodate the ground plain legs.

73


Hi Andy,

While the question of radials hinged on the match, sloping radials
raising the resistance; what you propose may raise it further yet. The
radials serve a purpose. If you remove them, you need to replace
their function by some other means.

This isn't bad, but it needs to be recognized and anticipated.
Basically you are moving towards a vertical dipole (albeit with one
leg at 5/8ths length). Even more, the lower leg will probably be
driven into ground (not the normal convention for vertical dipoles).
Even more, more, there is the drive line. It will contribute its own
variation to the drivepoint impedance unless you have it properly
choked.

The long and short of it, is that it may take some experimentation for
the right length of the supporting mast if you tie off the drive point
to it (instead of simply using if for support).

If you don't choke the feedpoint, then your coax will become part of
the tuned system. This is not bad (unless it gets back into your
equipment in the shack, or in the house in general), but it will
introduced a hard to control variability.

73's
Richard Clark, KB7QHC