> Isn't it mostly about being able to make a really good
> sliding contact
> to the two flat sides?
The factors that affect optimum form factor of an inductor
would fill a good sized book, but the edge wound tape does
two good things besides the obvious mechanical tap
attachment advantage.
First, the turn-to-turn center spacing can be smaller
without increasing turn-to-turn capacitance to the value of
tubing. Turn-to-turn capacitance kills Q in high reactance
inductors. A more compact length increases mutual coupling
from end-to-end and reduces inductor physical length for a
given inductance and current rating.
Second, eddy currents decrease. This also increases
inductance for a given size and reduces heat and loss
resistance.
Measuring edge wounds and tubing or round wire in a good
test fixture with good gear at HF, I find edge wounds have
about the highest Q of any inductor I've ever
tested...generally up in the area of Q=1000.
While we can do very well with tubing in low or moderate
reactance inductors and we might not need the additional
component Q when the operating Q of the system is low, there
isn't much bad about them and they are easy to find and easy
to work with. They even work well in the rain.
73 Tom
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