Bill Sabin W0IYH posted an enlightening comment on this topic just a
month ago in this newsgroup. Look in groups.google.com for his posting
on April 27. The topic was " Shielded inductors -- why do they work
so well?"

Roy Lewallen, W7EL

MarkAren wrote:
Hi All,

I keep noticing something which looks odd to me - I am sure it is
correct because this appears to be standard practice, but I would
appreciate it if someone could shed some light on the reasons...

Take a peek at http://web.telia.com/~u85920178/tx/500w-txt.htm (first
example I found). Specifically look at the 5 position switch on the
output matching, in position 5, the bulk of the inductor is shorted
out. This just looks plain wrong to me.

I assume that having shorted turns on an inductor like this drops the Q
drastically, or is this the whole point ?

Is the same true for roller coaster type variable inductors ?

Comments appreciated.

Thanks,

Mark.