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Re: Static Spark Gap



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Glen,

Cres for your NST is 10.6nf so your 9.4nf will be close to resonance and STR. Yes, you can operate there safely, but only if your safety gap/main gap are set correctly. The procedure you mention below is correct for the main gap. For the safety gap, same procedure but adjust until the safety gap just barely doesnt arc. The BPS will be high with this Cp so you need to watch the heating of your caps. Javatc can help with a BPS prediction, Imax in the primary, and energy transfer time. You can estimate the RMS current using these values and given whatever notch you quench at. Once the MMC is added, it will charge to the voltage breakdown setting of the main SG.

If Im interpreting your last questions correctly, you will need to tune your primary at low power and maybe a closer main gap setting (to let it fire at lower power) before you go to full power. Tune for longest arcs from the secondary top to a grounded target.

If you power up to full power with the secondary out of tune (no sparks from it), the primary arcing will be enormously loud and bright. If out of tune, you also risk getting racing arcs up and down the secondary that can damage the coil.

Gerry R.


Original poster: "Glen McGowan" <glen.mcgowan@xxxxxxxxx>

First the general question, Does every arc "Beat"?

I've got a 15/60 NST and an .0094uf MMC. I know it's not LTR, thats my problem. It's possible to adjust my SG so that the voltage is safe for the NST (at cost of spark length). But I'm sure how I'd go about doing this. Should I hook up the NST to the SG by itself (No MMC) and adjust until I get a nice consistant spark? and if I do it this way how would the MMC build up a charge if the Gap fires at the voltage comfortable for the NST? Which lead to my initial question, How can I tell if the arc is "beating" or just arcing?. How will I know if I'm charging and discharging my caps?