Re: Water absorbtion of Gray PVC

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Ed :)

On 10 Dec 2003, at 17:47, Tesla list wrote:

 > Original poster: Ed Phillips <evp-at-pacbell-dot-net>
 >
 > "In the end, it boils down to just how far you want to push the coil
 > voltage-wise. A short coil pushed to several hundred kV is naturally
 > going to need all the help it can get to maintain its integrity. You
 > can eliminate all the baggage by building a much larger coil so it
 > doesn't get tested in this fashion. You will likely also get better
 > results with ease as you boost its inductance, wiresize and
 > capacitance and lower its frequency. That is the approach I took with
 > that coil and it worked well. For the record, the secondary is 10"
 > diameter, about 4' high, has a loathed helical primary and produces
 > strong hot 5' discharges with just a kW or so of input.
 >
 > Malcolm"
 >
 >  Please give more details on your loathed primary!  Do you hate it
 >  that
 > much?  How much power is "just a kW or so"?
 > Ed

Oh, definitely not loathed by me - mainly some others on the list ;)
It works jolly well. There is a trick however and since someone asked
for a guideline on primary size vs secondary size, here is a guide
for this type of primary: height about 8% the height of the
secondary, bottom turn at the same height as the bottom turn of the
secondary, and diameter about 2.5x the diameter of the secondary. The
coupling constant was originally about 0.12 but increased somewhat
when I added another turn to bring it from 3 to 4 which increased its
inductance by about 50% to match some extra topload I added to the
secondary. Power draw varies considerably depending on whether the
streamers are attached or not from about 800W (air) to around 1.3kW
(attached). I still think I haven't achieved optimum results with
this coil and transformer but since it no longer belongs to me, I'm
done with modifying it. I plan to build better one of about the same
size for home use.

Malcolm