> I have a question, unless there is a "slit" cut
> down one side of this copper tube wouldn't it
> (the copper tube) also act as a shorted turn?
Absolutely!
If you don't slot the length of the metal tube near the active area of
the coil there is a "shorted turn effect" that reduces Q and
increases circulating currents.
There is also a Q reduction from additional stay capacitance, but
the major detrimental effect is magnetic flux related.
The screwdriver antennas I've seen aren't nearly as efficient nor do
they handle as much power as they could if the tube was slotted
for some distance away from the coil contact end.
73, Tom W8JI
W8JI@contesting.com
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