"Zommbee" wrote in
:

Hello all - I hope someone can help me figure this one out:
....

Dave,

I guess that you are hoping that with radials sloped down at 45 deg, you
should approach a 50 ohm feedpoint at resonance.

My experience is that sloping the radials tunes them high, in other
words, they need to be a little longer than were they are 90 deg to the
vertical element. Try clipping a short length of wire (say a couple of
feet) to the ends of the radial, just hanging down, and see what it does
to the feedpoint impedance. You can slide them away from the end to
lessen the effect. The outcome might just give you a hint of what needs
to be done. Remember, measure twice, cut once!

Re the tuner loss, they should be very low for the VSWR you have
discussed. Nevertheless, if you planned to have an antenna that shouldn't
need a tuner, I can understand why you might want to pursue the reasons
why or why not. It is an excuse for learning or frustration, depending on
your point of view.

As a matter of principle, I avoid using tuners like the '440's, they are
the achilles heel of those radios when the relays become unreliable.

BTW, one of the techniques for obtaining a match to 50 ohm feedline from
a groundplane antenna is to tune it a little high, and shunt the
feedpoint with an inductor or s/c stub. I drafted some notes on the topic
at http://www.vk1od.net/QWVmatch/QWVmatch.htm . This is probably not the
answer to your problem, since your 45 deg radials should lift the
feedpoint Z close enough to 50 ohms and closer than VSWR=1.5 that you are
observing right now.

Owen