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Re: First Light

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Alex,
Congrats on first light! Nice coil! One bit I wanted to add regarding gap cooling. When the gaps are at room temp (nice a cool) and the coil does very well for the first few seconds then quickly diminishes the spark length, you can be sure there is a cooling problem. As the gap heats up from successive bangs, the voltage required to arc the gap drops (that's the reason the sparks diminish). If the coil spark length is the same at startup as it is after say 10 to 20 seconds of running, cooling is probably not the issue.
In that case, I would recommend starting at the beginning (electrically). Check the NST's individually to ensure one of them is not 1/2 dead and robbing power. For example, do both NST's perform the same when run without the other without any changes to the gap and coil? etc..
There's other things to check, but it's always good to verify input power to the coil. It's very easy to kill a 10/30 NST especially during setup of a new coil, new gap construction, etc..
BTW, the secondary appears to me from the pics to be a 4.5" x 21" secondary and a primary using 0.375" tubing? Just wanted to verify as those particulars were not listed. 

Take care,
Bart

Tesla list wrote:


Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

Hey there, Alex:  I like to look of your coil.  Nicely
put together!

I wonder if your streamer length issues might be
gap-related?  70mA is plenty of current.  You probably
want a real good air blast across the gaps.  I've
never built an RQ-style gap before, but it's never
occurred to me that they'd really quench all that well
at higher powers; an air blast from one end is just
going to push the arcs along the tubes rather than
force them to stretch and snap.  I forget who did it,
but somebody on the list built an RQ-style gap with
big slots cut in the sides so that the air was forced
to blast out the sides across the broad faces of the
tubes (where they face each other).  That seems like a
much better design if you're expecting active
quenching.  Otherwise, I'd tend to think your airflow
is just cooling the gap and not really blowing the arc
out.  This will be fine and good at real low powers,
but with 70mA you're probably going to want more
blowing-out-type action.

Regards,
Aaron, N7OE

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Alex July"
> <julez06@xxxxxxxxxxxxxx>
>
> Well this is my first tesla coil (that works), it
> has two 10,000v
> transformers in parralel producing 70ma total. the
> capacitors are 0.03
> maxwells. The sparkgap is an RQ type. It is tuned ar
> turn 7.5 of 10,
> there are 1200 turns on the secondary of 26awg wire
> and a 5" minor 18"
> major diameter aluminium ducting toroid. however I
> cant seem to get
> any streamers longer than about 15" there are lots
> of sparks but they
> are short. Never the less i can feel another coming
> on... You can see
> it here:
> http://s164.photobucket.com/albums/u17/mi_july/
>
>
>
>
>