RE: Noob Question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: ben eells <squeels2171@xxxxxxxxx>

I finished my MMC and it increased the streamer length as well as the 
number of streamers. It didn't fix my problem I've been having 
though. The only info I can think to add about this problem is that 
if I leave the coil alone for a day and try it again after a long 
rest it will run for quite a long time before the problem starts back 
up. Also, what can be done to make my coil produce only 1 streamer again?

Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: "Lau, Gary"


Comments interspersed:

> Original poster: Jared E Dwarshuis
>
> Capacitors die quickly when coils are out of tune, or when you get
> primary strikes. (The symptoms you describe do sound a lot like
> failing tank capacitors.)

I can see how stress on the cap incre ases when out of tune - if the
power consumed isn't going into sparks, it must be languishing in the
tank circuit, mostly burned off in the gap but also in cap losses. But
I'm unaware of any data or theory showing that primary strikes can
threaten a cap. Conservation of energy just won't allow the primary cap
to be charged to a voltage exceeding its initial bang voltage.



> It is well worth the extra time to make a jacobs ladder from
> coathangers to test the output of your NST. Over time NST can get
> weak. This can also cause hard starting and general poor performance.
>
> Some people swear by RF filters. My personal feeling is that they are
> only usefull for coils that are being tuned.
> (no real data is available on the topic of RF filters for increasing
> the longevity of NST, just opinions!)

Agree 1000% on data and RF filters. My opinions at
http://www.laushaus.com/tesla/protection.htm.

My take is that setting the main gap too wide is likely responsible for
most NST and cap failures, and filters won't help if one lacks the
discipline to set the main and safety gaps properly. Most newbies
(noobs??) see the gap width as just another variable to tweak for
maximum performance, not realizing that setting it too wide just once
may be fatal to their hardware.

Diagnosing a suspect NST is relatively easy - just see if you can draw
an arc from each HV bushing to the case. Assuming a midpoint-grounded
secondary, both sides should be about the same.

Diagnosing a suspect cap isn't so easy. It may test fine on any sort of
capacitance or leakage meter, and only fail in TC operation at HV. Only
by swapping with another known-good cap (or by eliminating all other
possibilities) can one be sure.


> I do hope that you are using a safety gap, lack of such a gap leads to
> tank failures during initial tuning.
>
> Sincerely: Jared Dwarshuis

Regards, Gary Lau
MA, USA