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Re: [TCML] Q: Why won't this work better?
Chris -
Looks like a number of things may need attention:
1. Replace the single segment spark gap with a parallel-copper-pipe gap utilizing at least 4-5 gap segments with a spacing of around .025" between each pipe. Build a housing for the gap so that all the air from the blower is forced through the gaps, not just blowing in the general direction of the gap.
2. Simplify the wiring in the tank circuit between the primary, MMC, and spark gap. Currently you have what appears to be many connections with poor current-carrying capacity, especially around the spark gap: steel "L" brackets to steel screws to zinc drawer pulls, etc. Don't use crimp terminals unless you also solder them. If your large screw-clamp-terminals are aluminum, get rid of them, replacing them with direct soldered connections.
3. Replace any small-gage wiring in the primary circuit with a #10 AWG solid copper wire.
4. Are you absolutely sure that both of your NSTs are generating full output voltage? Check the output voltage of each NST, preferably using a HV probe, but can also be done by just checking the maximum arc length that can be generated directly across the HV output bushings.
5. Are you absolutely sure that the outputs of your NSTs are properly phased? Just wiring up the input and output terminals in "parallel" will not guarantee proper phasing. Individually disconnect each NST from the coil, and verify that the coil will run on each NST alone, and that coil output gets visibly better when both NSTs are connected.
6. There's some discrepancy in your NST voltage ratings that may have affected your tank capacitor callculations. Your schematic shows 7.5KV, while your TeslaMap spreadsheet shows 8.75KV. The ballpark "larger-than-resonant" tank capacitor value for a 7.5KV, 60ma power supply used with a static gap is .032uF, not .025uF.
7. It looks like you are using C-D 942 series caps in your MMC, probably the .15uF, 2KV rated parts. You only have six caps in your MMC, presumably all connected in a single series string to yield .025uF. Two problems here: not enough current carrying capability, and not enough voltage margin. You need at least two parallel strings, and enough caps in each string to provide a DC voltage rating of at least 18-20KV. Your 7.5KV RMS output voltage creates a peak voltage of 10.6KV, and your cap string is only rated at 12KV. If you use a variac to boost the input voltage to yield an 8.75KV RMS output voltage, the resulting peak voltage is around 12.4KV, exceeding the capacitor's rating.
8. You don't describe your secondary ground setup, but make sure that you have an effective earth ground, and a short, low impediance connection between secondary and ground.
9. Get rid of all the sharp edges and points at the end of the innermost primary turn. Everything here must be smooth and well-radiused, otherwise you will leak corona and eventually arc over to your secondary, likely damaging it.
10. You said you replaced the spherical topload with a toroid, but did you also get rid of the foil-covered squat cylinder at the top of the secondary? The relatively sharp edges will also leak corona and subtract from streamer length. Think "minimum radius of curvature" for all conductors and surfaces carrying HV.
I'd concentrate first on verifying your NST output voltage and phasing, and improving your spark gap. Your MMC will also require an upgrade. You might also want to measure the capacitance of each cap in your MMC; if you've been abusing them with overvoltage for a year, they may have suffered so many dielectric punctures that they have lost measurable capacitance.
Quarkster
--- On Mon, 7/4/11, Reverend Fuzzy <pastor@xxxxxxxxxxxxxxxxx> wrote:
From: Reverend Fuzzy <pastor@xxxxxxxxxxxxxxxxx>
Subject: [TCML] Q: Why won't this work better?
To: "Pupman Tesla List (Pupman Tesla List)" <tesla@xxxxxxxxxx>
Date: Monday, July 4, 2011, 10:11 AM
I've been dealing with a 3.5" SG coil for close to a year now, and can't get better than 12 to 15 inches of streamer length out of
it. The various programs I've tried say that I should be getting between 30 to 40 inch streamers. Pics and notes can be seen
on-line
At: http://www.msbministries.org/galleries/msb3/index.htm
Please note that it no longer uses the spherical topload shown in the pictures, but instead uses the toroidal one specified in the
tech notes.
Thanx a meg in advance for all constructive input.
---
Reverend Christopher "Fuzzy" Mayeux
Pastor, MSB Ministries
Hattiesburg, MS
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