Re: Fine tuning

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

Original poster: Esondrmn-at-aol-dot-com 

In a message dated 2/19/04 6:44:21 PM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:

I recently measured the resonant frequency of my 3" coil using Bart's tuner 
(Terry's design I believe).  The secondary measured 310 khz, calculated was 
300 khz, and the primary measured 271 khz.  That is 12% lower in frequency 
than the secondary.  The calculated tap point was at turn 8.0 on the 
primary and the actual tune point for best performance is turn 8.6 which is 
where the frequency was measured.  Demonstrating, as Gary says below, the 
scope will get you in the ball park but best performance will be achieved 
with the primary set to a lower frequency than calculated to compensate for 
the secondary streamer loading.

Ed Sonderman

>I assume that you've already tried rough tuning of various primary tap
>connections.  If the performance is still thought to be considerably
>less than it should, I would look at the overall design features:  Gap
>design, topload size, pri-sec coupling, capacitor specifics.
>
>Despite the apparent precision of signal generator & scope tuning, final
>tuning is still done the old fashioned way - changing primary taps for
>maximum performance.  The secondary frequency is significantly affected
>(lowered) by the presence of streamers, so low voltage instrument tuning
>will just get you in the ballpark.
>
>Gary Lau
>MA, USA
>
>
>Original poster: "Steve Zeitler" <zeitler-at-verizon-dot-net>
>
>hello everyone
>i haven't been on this list for a while.
>I built a coil in '96 which wound up at the Museum where I work . It has
>
>worked OK but was never a stellar performer.
>Recently It fried 1 of 2 homemade power transformers. (they were 9kv
>-at-150ma
>+/- if not ballasted. They were connected  in series. I was able to
>obtain
>2 "potential transformers" from the local power company 8.4kv at 1500va
>each. These are a good scrounge right? I will run these in series also.
>the tuning was set during construction based on signal generator and
>o'scope testing. Close but not right on I'm sure.
>My question is, how do I fine tune this machine  to get best performance
>
>out of it? surely there is an article someone can refer me to.    Thanks
>                                                         Steve Z
>                                                  The Franklin Institute
>                                                         Philly