> We tried both a couple of short jumpers at the top of
> the tower to the feedpoint and then a ~130 foot piece of
> RG213 from the feedpoint to the base of the tower.
>
Did you get the periodic variation in impedance (800 KHz
to 1 MHz periodicity) when you measured from the top
of the tower, or just when you measured from base with
the 130' coax?
>
> >4) Are you sure the metal strips that form the parallel
> >feedline on the 40 meter dual driven element aren't
> >shorted together?
>
> 99.9% yes. K4JNY checked that on the tower yesterday.
>
I would try disconnecting the phasing lines and feeding each
one of the driven elements by themselves with no balun, or
with a known good 1:1 balun. If this doesn't give a VSWR
dip at or near 7 MHz, then I would start to suspect a problem
with the linear loading stubs on the driven elements. Of
course, if you can easily rotate the 10 meter antenna by 90
degrees you might want to do this just to get it out of the
way, but I would be very surprised if the 10 meter antenna
is the problem.
Good luck!
Mike, W4EF....................................
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