[TCML] NST rebuild good

mark olson kc5gym at cox.net
Tue Jan 8 20:09:58 MST 2008


>
>
>The cap is totally STR by about 1.7 ratio. I don't see a problem with 
>that, but I do see a problem with your main gap (and this is probably what 
>killed the NST in the first place, especially if the safety gap was wider 
>than it is now). The question I have is why isn't the main gap firing? How 
>is your main gap configured? Total gap spacing? Also, what type of 
>electrodes are you using for the safety gap? It sounds to me like your 
>safety gap is simply arcing sooner than your main gap. Safety gaps may pop 
>now and then, but not like a firecracker. If that's the case, the main gap 
>is not performing it's function.
>
>Take care,
>Bart
My gap is built like a box with a stationary electrode in each corner.  The 
electrodes are paralleled two per side.
The left side of the box electrodes are paired, and the right side are 
paired. The flying electrode lines up diagonally
with the stationary electrodes four times per revolution.

The gaps were approximately..015" for a total of about .030"




electrodes are made of 1/8" welding tungstens.


The coil works fine until the safety gap begins to fire.  As I approach the 
critical voltage, the safety gap pops now and
then,  which can be reduced or eliminated by adjusting the gap synch.  When 
critical voltage is reached, about 80v,
the safety gap breaks down and fires rapidly. At that point, the rotary gap 
misfires at the same rate that the safety
gap fires.

The safety gaps are made from brass drawer pull knobs about 1.25" diameter 
with spherical faces which I estimate
to be about 6" radius.  They are polished.

You've caused me to realize that the safety breaks down while the rotary 
gaps are larger (not lined up) but
the rotary gap performs flawlessly with no tank.

I do not know exactly what may cause this, but it may be resonant kickback 
or something causing voltage peaks
out of phase or off 60 hz.

Thanks,

Marko 




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