George (K8GG) wrote:
"Keeping the 160 meter inverted-L connected to ground through the
windings
prevents it from being a resonant half wave floating wire on 80 when
using
the 80 meter vertical nearby"
Whether the connection would appear as a ground would depend on the
winding used and the coax connection. It would be possible for a
combination of a length of coax and the winding used to appear as a
parallel resonant circuit on 80m, putting the antenna in play as a
parasitic element.
Check whether the coax/winding combo "grounds" the antenna by checking
with an analyzer looking at the shack through everything, with that
antenna NOT selected at the antenna switch. Particularly if the Z is
very low, it could still be subject to the voltage issues raised
earlier by W8JI at the other end of the coax. Would be at its worst if
the electrical length to the switch is an odd multiple of a quarter
wave on 80m.
Even without that, the Z measured by the analyzer should be put in a
model containing the two. Place the measured Z in a load at the base
of the inverted-L and run it. Interactions seem to mostly be worse
than thought.
Positive relay action at the feed point to short to ground is still
best.
73, Guy.
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