Re: Space Winding - was What to look for...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>
> 
> Hi John,
> 
> Tesla list wrote:
> 
> > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <FutureT-at-aol-dot-com>
> 
> > One can use thinner wire for the spacewound coil, and keep the
> > inductance high, yet reduce the proximity effect.  According to
> > Terman and other experts, such a coil will show lower losses
> > than a closewound coil with thicker wire, both having the same number
> > of turns, and the same coil length.  A 50% to 70% wire "fill" factor
> > was deemed to be best.
> >
> > John Freau
> 
> This is an interesting idea! I'm assuming the filler wire is wound
without any
> connection (simply a filler)?
> 
> Bart

	The 50% to 70% wire "fill" factor is for coils working at higher
frequencies, where skin effect in large wires limits the Q.  In my
opinion, in the region of 200 kHz or less the difference in losses is
not worth the nuisance of trying to space wind the turns.  I have wound
a couple of antenna loading coils for use at 181 kHz.  The wire size was
#28 and the coil diameter was 5.5".  The space-wound coil (used
monofilament fishing line for the spacing and removed it after the
windings has been doped) and the other coil was close wound.  Couldn't
measure the difference in Q, which was around 400 at the operating
frequency.This is neglecting the fact that, at least (again in my
opinion)  the unloaded Q of the secondary isn't of much importance when
the effects of streamer loading are included.

Ed