Raised secondary problems

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

Original poster: "Jolyon Vater Cox by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

I have conducted some experiments using the primary shown in

http://hot-streamer-dot-com/temp/P001800.jpg

to drive
a secondary of 880t of 32SWG enamelled copper wire wound on a  2.9" dia 
former; the primary being grounded at the centre and tapped at the sixth 
turn for best match.

Here are my findings:-

When the base of secondary is approximately 1 1/2" below the primary
6" or so long sparks can be drawn from the TC to a pointed electrode when a 
16 1/5" dia, 1 1/4 rim bicycle wheel is used for a topload.

When the secondary is raised with respect to the primary (so that it is 1 
1/2" ABOVE the primary) the spark length falls considerably -it is pitiful- 
and it is not possible to compensate for this by increasing the number of 
turns to the tapping point on the primary.

However, when the primary is raised with regard to the secondary by only 1" 
or less arcing occurs between the base of the primary and the secondary 
winding?


The experiment has conducted twice and the same things happened.

Is this a matter of under- and over- coupling?  My intention was to support 
the secondary on a platform 1 1/2" inches above the secondary
but my experience suggests this is not possible without severely reducing 
the spark length.


Is there a way of getting 6" or so sparks with the secondary raised above 
the primary in the manner described
e.g. by increasing the number of secondary turns -possibly by using finer 
wire like 40SWG
or by using a larger tank capacitor -I am currently using 22nF and would 
rather not have to build anything larger than this!

Or is the whole idea of raising the secondary a bad idea that should be 
abandoned in favour of the present arrangement?
Jolyon