Re: MMC Caps (and toroid availability)

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

> 
>  I'm saving up some money to buy the GeekGroups MMC Caps but I have a
>  question regarding the table on their website.  The table has three 
columns:
>  resonant cap, static gap LTR cap, SRSG LTR cap.  I understand the 
difference
>  between static and SRSG but what does LTR mean and how many would I need?
>  I'm running from a 12k 30ma NST with a RQ spark gap.
>  Thanks
>  Dave

Dave, all,

note to coilers: [ I have just one 1 3/4" x 6" spun aluminum toroid left ]

LTR means Larger Than Resonant.  A cap of this value can be
used instead of a resonant or matched value, to keep the voltage
lower on the NST (if you're using NST power).  NST's tend to
be destroyed by high voltages, and the voltage can go quite
high with a resonant value cap.  For example, my TT-42 TC
uses a 0.0147uF LTR value cap for the 12/30 NST.  I used to
use 0.007uF which was closer to the matched size, but this
larger 0.0147uF value keeps the voltage lower which may
protect the NST.  You can of course keep the voltage low
on the NST even with a matched value cap, by using a narrow
gap spacing using a static gap, but this will decrease the 
overall spark length.  I obtained the same 42" spark length with 
matched or LTR caps on my coil.  I use a sync rotary gap. 
My TT-42 coil can be seen at:

  http://hometown.aol-dot-com/futuret/page3.html

The LTR value can be larger when a sync gap is used than
when a static gap is used.  For a sync gap up to 2.5x the
matched value may work well.  For a static gap perhaps
2x the matched size may be dandy.  If you use a triggered
gap, this would use a cap value similar to a sync gap LTR
value.

John Freau