In article ,
coffelt2 wrote:

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

My understanding is that the presence of the shorted turns in the coil
does lower the Q of the coil somewhat. If the loaded Q of the
system/application is already low enough, the reduction in coil Q
doesn't result in an unacceptable increase in losses.

The alternative, in some cases, is to leave the unused turns open at
one end. This isn't always possible, and when it is possible it can
have an unfortunate side effect. Autotransformer action can cause the
open end of the turns to develop a high voltage relative to the rest
of the system, and there can be arcing to nearby points of lower
potential. Could make a mess of the inside of your transmatch :-(

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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