Flat Coil Q vs Solenoid

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

Original poster: "Steve Greenfield by way of Terry Fritz <twftesla-at-qwest-dot-net>" <alienrelics-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "John Tomacic by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <tesla_ownz_u-at-hotmail-dot-com>
> 
> All these postings about flat secondary coils made
> me take a quick look at 
> the inductance of a flat coil and compare it to a
> helical coil I already 
> have.  Surprisingly, the inductance of the flat
> spiral coil is 60% higher 
> for the same length of wire. In this case the length
> of wire is 1478 feet.  
> Since the wire resistance is the same for both
> coils, is it safe to conclude 
> that the Q of the spiral would be 60% higher seeing
> that Q is proportional 
> to XL/R?
> If so, then there is an advantage to using flat
> spirals as secondaries, 

Not my experience, but on the Crystal Radio list it
seems to be the consensus that spiderweb wound coils
have lower Q than a properly proportioned solenoid
coil. But I have not personally tried to measure it or
seen where anyone else has done so.

http://clubs.yahoo-dot-com/clubs/thecrystalsetradioclub

You ought to try and get some of them to try picking
up Tesla coil transmissions... Modulate it the old
way, connect a carbon microphone between ground and
the bottom of the secondary or primary. ;') <eg>

Steve Greenfield