On Mon, 28 Sep 2009 19:33:12 -0400, Bill M
wrote:

Peter Dettmann wrote:
On Sun, 27 Sep 2009 22:28:33 -0700 (PDT), K7ITM wrote:

On Sep 26, 8:25 pm, brian whatcott wrote:
rtfm wrote:
On 2009-09-24, Tomylavitesse wrote:
HI,
OK?

snip

As well, it would be interesting to see the effect of stray
capacitance, as the reason for shorting unused turns is to reduce the
problem of stray capacitance and the inductance having unwanted
parasitic resonances in the system, That is why shorting unused
sections is normally advocated.

Peter Dettmann


Well, its the better of the options but the Q of the 'desired' coil
still takes a hit because of that nearby lump of copper.

It works out ok in practice, though.

-Bill

Exactly Bill, and the whole thing really is a matter of just what is
the needed, or acceptable Q. If the Q is satisfactory with the
shorted turns, then that is the way to make your design (keeping in
mind the disadvantages of open circuit unused turns).

However should you need the highest obtainable Q, then a single
isolated coil is called for which has the needed turns.

Peter