Re: Rotary Vs Stationary

In a message dated 99-06-10 01:18:09 EDT, you write:

<< 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