Owen Duffy wrote:

Cecil Moore wrote:
You already know what I am trying to say. I must not be saying it
very well. When a parallel cap is used on a 75m screwdriver antenna
to achieve 50 ohms, the screwdriver is tuned to 1/50 + j1/X, i.e.
^ should be -
slightly inductive. When a parallel coil is used, the screwdriver
is tuned to 1/50 - j1/X, i.e. slightly capacitive.
^ should be +
Negative susceptances are inductive. An inductive reactance of j5 is a
susceptance of 1/j5 or -j1/5.

I agree with your words, the sign of the admittances is wrong.

Yes, you are correct - sorry. But it now seems that you understand
what I was trying to say. If one takes an ordinary G5RV and
installs a parallel 1000pf capacitor at the coax/twinlead junction,
one will raise the resonant frequency and lower the SWR on the
coax for 75m operation. Very close to 50+j0 ohms can be achieved
on 75m through that simple act. When I lived in AZ, I switched that
cap in automatically using a relay and the frequency output signal
on my IC-745.
--
73, Cecil http://www.qsl.net/w5dxp