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Re: [TCML] BPS Testing

Hi Gary,

I failed to state the test configuration. Here it is:

Sec= 4.5" x 21.81", 24Awg, 895 turns.
Pri= 7.5" x 16.5", flat spiral, 9 turns, tapped at 8.5
Pri Cap= .0188uF (this is 1.77 x the res cap size)
Toroid= 6.25" x 21" (minor and major diameters)

Gap= RQ style, 6 tubes (1.25" Diam., .050" spacing, 0.25" total gap width) w/lots of air cooling.

NST= 2 x 15/30's in parallel (no variac, no safety gap, 120Vac input directly at wall plug). Identical Franceformers.

Spark lengths were not as good as my main modified NST, but ok at 40" average free air sparks. I wasn't doing a spark length test, but did notice the sparks relative lengths and a couple strikes to my air compressor 45" from the toroid.

The BPS is low. The 12.7 second test confirmed 80 bps. Given the rate of charge, cap size, and arc voltage for gap geometry, I calc'd 70 bps for this static gap. I can understand the 80 bps value. Also, I could "hear" the bps rate was low and this test confirmed it.

As you know I've had a problem with the high bps rates stated. In our near last conversation on this topic you asked me "have you ever measured it?". Well, now I can say "yep".

I'm curious more about your measurements and setup at this point to try to explain the high bps you measured. Either current is higher (modified NST? or maybe the gap itself is the cause?). I don't know, just stumbling in the dark to explain it. There has to be a logical reason for it and if it was something seen by all coils, then I should have measured at least 120 to 150 bps, but I didn't. So from my perspective at this point, not all systems will see a high bps to what is predicted.

Take care,

Lau, Gary wrote:
Hi Bart,

I missed the basic test configuration that you're using.  Two 15/30's, but what size cap?  Gap geometry?  Did the coil perform well?  82 or 70 BPS seems low for a well performing coil.

Regards, Gary
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