Hi David,
JavaTC suggests the optimal coupling is in the 0.14 range. However, for my prior, now extinct secondary, I got killer arcs when I got close to that. Could have been cause by other issues - like the fact I put 0.12uF of cap in the tank. (now running 0.06uF) But I'm wary of higher k. Every time I mess with getting close to 0.14 or 0.13, I get badness.
I am going to measure the k directly, today, and will post the numbers.
Cheers,
Joe
On Oct 23, 2010, at 4:24 AM, David Rieben wrote:
Hi Joe,
Although this has nothing to do with your Dolphs "bubbling up
on you", I did notice that your physical primary/secondary coupling
looks rather loose to me. Your calculated k = .09 is probably "in
the ballpark" but to my understanding, around .12 to .15 is usually
considered in the optimal range for medium to larger SG driven
coils. IIRC, the top plane of the copper tubing primary of my
Green Monster coil system lies only about 1.5" below the level
of my lowest seondary turn and this seems to work great for me
(no racing sparks but plenty of good energy transfer).
David Rieben
----- Original Message ----- From: "Joe Mastroianni"<joe@xxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List"<tesla@xxxxxxxxxx>
Sent: Friday, October 22, 2010 8:18 PM
Subject: [TCML] Coil V5 - first light
http://yfrog.com/n2rrfj
8.5" x 34" secondary. 919 turns of heavy build 20ga. 6" x 24" toroid
Using the same dreaded ribbon primary because I didn't want to have to build a new one yet. Spacing between the top of the ribbon and the first turn of the secondary is 3.75". k=0.09 calculated (not yet measured). ARSG. Pig running at about 30A.
Sparks seem to be in the 6-7' range, but have yet to mount the larger toroid I'm working on.
Basically, needed to replace my 6.25"x24" secondary that burned last weekend.
Problem with this secondary is that the Dolphs bubbled up on me. It went on w/o bubbles, and they emerged later. I coated all week, at least 1 coat per day. Could it have happened because it is much colder out then when I wound my prior secondaries?
Cheers,
Joe_______________________________________________
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