Roy,

Several weeks back, and confirmed by frequency sweep model runs, you indicated
that minimum impedance is close or equal to the resonance point. I tuned the
antenna to the frequency of interest and then used the Autek to verify the
resonance point. That minimum value was 36 Ohms. I am assuming this is or is
very close to the resonance point for the antenna system.

What does your running of the model show for resonance frequency? At resonance
my running of the model shows close to 20 Ohms for the relatively large values
of R used in the model.

Thanks - Dan

Roy Lewallen wrote:
Frank's wrote:


Dan, I notice the Autek analyzer only measures the magnitude of the
impedance. With any of these lower cost instruments it is impossible
to find any accuracy specifications. The 8405A is an excellent
instrument, but assume you calibrated it -- short/open/load -- at the
end of the 100 ft cable. This calibration should also be carried out
on the antenna side of your isolation transformer when you install
it. Curious as to what kind of directional coupler you are using for
HF. I remember using a small HP coupler for HF, but cannot remember
its model number.

Frank


Hm, if the Autek measures only the magnitude of the impedance, how does
Dan know the resistance? The model shows about 133 ohms of reactance,
which is much greater than the resistance.

Roy Lewallen, W7EL