Re: LTR caps

[Terry Fritz <twftesla-at-uswest-dot-net>]

Hi Paul,

	If you have a static gap, the LTR value is about 1.5 to 2 times resonant
depending on how lossy the gap is.

	With a sync rotary gap, the values are higher in the 2.5-3 times resonant
range.

Cheers,

	Terry

At 10:26 AM 7/27/00 -0700, you wrote:
>     Terry, et al,
>     
>     I am a little confused about your recommendations for LTR cap sizes.  
>     
>     you say below 1.5 times the resonant size, but both the cap sizes you 
>     are using below and your excellent MMCcalc program give values closer 
>     to 2.5 times the resonant size.
>     
>     Thanks,
>     
>     Paul
>
>
>______________________________ Reply Separator 
>_________________________________
>Subject: RE: performance/tuning question
>Author:  "Tesla list" <tesla-at-pupman-dot-com> at INTERNET
>Date:    7/26/00 8:13 PM
>
>
>Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
>     
>     <snip>
>     
>The next is point about 1.5 times the resonant size (static gap) where the 
>NST list still able to charge the cap to the full NST rated peak voltage. 
>This is the "LTR" type coil we often speak of.  The trick here is to charge 
>a large cap to a specified voltage and take advantage of the increased 
>energy.  With a rotary gap, one can really tune the inductive kick effects 
>and use really large primary caps to get the full VA rating of the 
>transformer into the coil's primary.  Unfortunately, this tuning is a bit 
>tricky but tunable multi-string MMCs have mostly solved this.  My 15/60 LTR 
>coil uses a 24nF cap and my small 9/30 uses 27nF.  The resonant size caps 
>would be only 10.7nF and 8.84nF.  The 27nF cap stores three times the 
>energy and fires at 120BPS.  The 8.84 cap would have to fire at 360BPS for 
>the same power through put.  However, 360BPS does note "ring" well with the 
>60Hz line voltage so the throughput is worse due to erratic gap firing.
>LTR coils were literally born from line frequency timing theory so they are 
>truly optimal in this respect.  LTR coils do not over voltage the NST and 
>they only over current them a "little" (50%) which NSTs seem to take in 
>stride.  If the spark gap on an LTR sync coil fails, the voltage actually 
>drops about 30%...  It is interesting to note that the sync gap 
>configuration was "discovered" by computer modeling before the real 
>hardware was demostrated and "real" testing proved the computer's 
>prediction.  No "seat of the pants" stuff there! :-))
>     <snip>
>