In a message dated 98-07-06 19:07:11 EDT, you write:
<< >
Pete; A low point SWR does not indicate the resonance frequency of an
antenna. From what you describe, I'd bet on RF on the outside of the
feedline.
>>
I'd bet Pete has a 50 ohm bridge measuring a 75 ohm line. If that is the case,
SWR readings will change when line length is altered.
Remember, SWR will remain constant ONLY if the meter and line have the same
design Zo.
It's unlikely a very long feedline has enough common mode current left, no
matter how much common mode current is developed at the antenna, to cause a
large impedance shift at the feedpoint when the line length is altered far
from the antenna.
It's even more difficult (if not impossible) to find a meter sensitive to
common mode current.
73 Tom
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