Re: How to Tune a Flat Spiral Coil

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Dave - 

Tesla list wrote: 
>
> Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <dave-at-volantis-dot-org> 
>
> I can add, however, that when my flat spirals are out of 
> tune the spark gap cuts out during operation for a few seconds at a time.  I 
> didn't run the coil long enough at 2.5 turns to conclusively say that the 
> spark gap wouldn't have cut out, but it didn't during that time.




Just a note here. Gaps in helical coils can run eratic if far enough out of
tune. I'm not sure about cutting out completely (I don't think I've witnessed
that), but I have been far enough out of tune to get almost nothing on the
output (it's been a while, but if memory serves, the gap was dismal and safety
gaps were going off like mad - I obviously didn't leave it that way long). 

>
> Yes, the arcs occurred near the outer windings of the secondary. 
> Particularly the arcs occur at the three points where the three leads exit 
> the secondary.  I assume this is due to the weaker dielectric.




Yes, I think partially because of the dielectric, but maybe also due to the
higher inductance on the outer portions of the windings. 

Take care, 
Bart