Re: [TCML] Is tuning different for SRSG than for Static Gap?

[Brandon Garretson <garretsontech@xxxxxxxxx>]

Thank you Gary!
You gave me just the info I needed to move forward.
I will just short out the safety gap and use my TCT to get it close, I
have no problem with that.
I was mostly worried about having to find the sweet-spot within two or
three turns, but I think I
will likely find it within one turn or less if the tuning method
doesnt change with the SRSG.
My coil seems to be pretty sensitive to the tapping point...
As far as the increased cap goes, I actually overbuilt the cap,
acording to "Teslamap", when I started this project long ago in hopes
that I would someday add an SRSG. I just wasnt sure why it neede to
bigger....
My MMC is comprised of 75 .1 MFD 2Kvdc Cornell Dubiliers, 25 in series
by 3 sets parallel for a total of 12nf.
I guess the total capacitance was a little high for the static setup
but should be on the money for the SRSG.
I would assume that voltage shouldnt be an issue as the x-former
currently in use is a 12/30.
Thank you also for pointing out that increasing the topload could
quickly compensate for the size of the primary.
I will keep that in mind if I ever hit a tuning wall.

As an added note, if anybody is keeping record;
In regards to the Freau phase controller, I am using a 1/13 hp 1.3A
115V 1800rpm Xerox P/N 127K07993 synchronous motor
made by Reliance Electric and a 2.25A model 10C Powerstat.
It seems to work best with a 67MFD PFC throughout the full range.
Although both the motor and Powerstat do groan a little throughout the
middle part of the sweep.
I freeze-framed it with a strobe light (propeller type gap by the way)
and was able to achieve close to 45d of phase shift.
More or less capacitance doesnt seem to change the shift much, only
seems to effect voltage.
With 67MFD I get a 5V rise at aout "25", and at "98" on the Powerstat
it runs well at about 90V, at "100" it starts to stall out.
I also hooked up the transformer (only) to the SRSG with the strobe
flashing on it and was able to watch how the spark reacts before and
after the stationary electrodes while shifting the phase.
Thanks to my background knowledge of automobile ignition systems it
came as common sense to me that I would want the timing to be slightly
retarded as the arc occurs prior to the electrodes centering.

Thank you again for the info. I have been reading the Pupman archives
for about two years now and Im very happy with the answers to my first
posted question!



On Fri, Mar 12, 2010 at 7:54 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> Hi Brandon,
>
> As far as tuning the primary & secondary resonant frequencies, no,  the type of gap wouldn't matter.  Despite having all sorts of test equipment available, once I'm in the ballpark with the design, I always use trial & error to select the best primary tap point.
>
> You should realize that when moving from a static gap to an SRSG, the primary cap value needs to be higher with the SRSG, or else you'll overvolt the cap & NST.  So with the same NST and secondary system, you'd need a larger primary cap and comparably smaller primary.  Of use the occasion to upsize your topload to compensate.
>
> I'm glad to hear that you're using a Freau phase controller.  While technically not tuning, I find that the RSG phase is extremely critical, and I use the phase control much like a Variac - set it to an early phase, then slowly advance it until it "goes out of whack", then back off a bit.
>
> Regards, Gary Lau
> MA, USA
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