Re: Rotary Vs Stationary

<<Original Poster: Michael Burton <mickb15-at-ozemail-dot-com.au> 
 >     Pardon my lack of knowdege,
 > I would like to know if a rotary spark gap HAS to be synchronous to be
 > successful?
 > and also, would there be much use in a RSG on a 4" coil? (are they mainly 
 > bigger coils?)
 >     Thanks, Michael >>
 A 4" coil can produce up to 64" sparks or longer, if you apply enough
 power, etc.  By using a sync rotary, you can get the most from an
 NST powered TC.  Many fine coils have been built without RSG's 
 in a range of sizes, although rotaries are generally used above 2kW
 or so.  Of course static gaps can function well at somewhat higher
 powers, but will have to be constructed more carefully to address
 cooling concerns, etc.  NST powered coils should not be used with
 non-sync rotaries, because the uneven firing leads to skipped firings,
 which requires wide safety gap settings which leads to NST
 IMO, the sync rotary is at it's best at 120bps, at 240 bps much of 
 the advantage is lost, and a non-sync rotary might perform about 
 as well, but I haven't done an absolute comparison yet.  
 For the typical coiler first migrating to a RSG system, who might
 be using a somewhat small cap, the higher break rates may give
 some advantage.  120bps sync systems need a relatively large
 cap for best results.  Or you can use a smaller cap and a higher
 voltage too, but then the caps, etc, need to be able to withstand
 the higher voltage.  It's the large bang size and low break rate that
 are important.  I have not tested the efficiency of 120 bps sync gaps
 at high powers, so I can't say for sure that they will continue to 
 excell as the power goes over 2kW.
 John Freau