Re: Fine tuning

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi,

Richard Hull always suggested to tune the primary 7% lower than the 
secondary to account for streamer loading.  In my case, that always seemed 
to work very well.  Then one can fiddle with it a bit to get the longest 
streamers, but it will be very close to start.  Also note that moving the 
coil to different areas can affect tuning a bit.

Cheers,

         Terry

At 11:29 AM 2/20/2004, you wrote:
>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
>