> What is the size of the secondary that you are using?

My secondary is a 4.5" x 18" fiberglass tube close wound with 450 
turns of #20 enamel covered magnet wire for a winding length of 14".  I 
have a aluminum toroid on top 10" across with a 2" diameter cross 
section (i.e. - the doughnut part is 2" across).  I'm running 10kV at about 
70mA into the primary.

Gap adventures:

I just bought a squirrel cage fan this past weekend to use with my 
multi-tube gap I am building, and last night I decided to try it out with 
my ball bearing gap to see if it made any difference.  It did...it blew my 
ball bearings off their holders (I just have them sitting on little ceramic 
insulators) so that was the end of that experiment.  I then tried the 
blower using an old single gap that I had made from two bolts. The 
secondary discharge with the blower on was about twice what I was 
getting with the blower off!  I didn't make any kind of quantitative 
measurements, but the forced air quenching really made a visible 
difference.  I then tried using a single spark plug as a gap.  It started 
firing relatively quietly at about 2kV, and turning the voltage up just 
started a power arc with no other visible affect.  When I had the voltage 
adjusted so that it was just firing nicely, I could draw a 2" spark off the 
secondary, but there was no free air discharge.  Whipping out my neon 
light indicator, I saw that I was getting about 10 discharges per 
half-cycle.  Pretty cool!  I also found some clear light bulbs and had 
some fun with the discharges (hold the metal base and get the bulb 
near the secondary terminal...you can see some real pretty streamers 
coming off the wires in the bulb).

And finally some questions:  Does anybody know how to measure the 
'Q' of a coil?  The TCBOR folks mention it in their guide, but don't say 
anything about how to do it.  Also, does anyone have the TCBOR 
instrumentation tape and if so, what does it cover?

Steven Roys (sroys-at-radiology.ab.umd.edu)