coffelt2 wrote:
"Tomylavitesse" wrote in message
...
HI,

Often I can see coils where some turns are shorted in order to modify
there value.
I wonder whether these shorted turns would not be seen as a short
cicuit and could decrease the quality of that coil.
How can I have an idea of the lost of quality without complex
equipment ? I plan to build this kind of coil for a shortened
antenna... regards

Good question! I've always wondered about that too. In a former life
as a marine electronics technician, the old marine "AM" transmitter
antenna tuners uses shorted turns a lot. It always sort of went
against the grain, I thought, but in practice, it seemed to work ok.
What was I missing here? Old Chief Lynn, W7LTQ and some commercials
with endorsements

In many military antenna tuners, the variable inductor inside the tuner was
open on one end. The coil was rotated such that the length of the coil
winding was changed, or the position of the tap was changed to effect the
tuning. There were also some tuners that spooled one end of the coil onto a
grounded metal drum. The mechanism changed the effective length of the
coil, but did not introduce any shorted turns.
--
David
masondg44 at comcast dot net