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4 Wonderful MMC/Gap questions



Original poster: "Matt S. by way of Terry Fritz <twftesla-at-uswest-dot-net>" <matt777777-at-hotmail-dot-com>

Hi,
I have been on and off gradually building my coil, and am finally at the 
Capacitor point, and have a couple of questions that I'm hoping people can 
help me with.  The construction has gone suprisingly well (for me) up to 
this point, and I'd like to have to solder caps/resistors only once (vision 
failing and what not).
I realize that these are pedestrian questions, but would very much 
appreciate some assistance.

My coil's specs:
12 kv 60 ma NST
4.24" x 23.25" secondary (22 ga wire.... pvc form, polyurethane, etc)
Primary is 1/4" cu tubing 15 turns 6.5" I.D., 20.5" o.d. 1/4 inch spacing 
(inclined 15 deg.)
Toroid is 17" dia., (4" dia. ducting)
Filter is modeled after Terry's (complete with MOVs even)
Gap (un-built, but will be static  -see below )


Question 1.
(probably a most common one):
I am wondering what size cap I should construct.
I have used Ed Sonderman's spreadsheet and E-tesla, and I think I am doing 
things correctly, but am hoping for some validation.
The program gave me a cap size of 8.33 nf
I have read that larger may be better, but I have no plans to build a rotary 
gap.  So..... I was wondering if I should target 8.33 nf or can I go up in 
size a bit (and if so, what would be a practical limit).
(any benefit to a LTR size cap without a rotary gap?)

Question 2.
I am using the same caps that Terry F. uses (Panasonic 1600V .056 uf) for my 
mmc, and originally settled on 4 (or 5) strings of 26 caps but that seems 
like a heck of a long string....... I have enough caps for that, and would 
rather have a bullet proof mmc, but ---> is there a point where too many 
caps per string degrade performance or create some kind of problem?

ok,... a couple more since I'm here:
Question 3.
Are 4 (or 5) strings adequate for the specs given?

Question 4. (non cap question)
The gap..... I sure am having trouble finding info on gap spacing.
Any recommendations for a good NST safe total gap spacing for a 12kv NST?
(also I would welcome suggestions on the optimum number of segments for a 
static gap too)

Sorry for the glut of ?'s and the relative lack of depth therein ....  
Obviously I am green to H.V. and coiling.....  But am looking forward to the 
"first light" feeling.
I welcome any replies (thanks in advance).
I'm prepared to face those little caplets with a look of false confidence 
(inspired by other's suggestions) so they don't sense my weakness.

Matt.

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