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Ultra7

Sat Apr 19 2008, 05:04PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Grab a jewel case from a CD and stack it on top of your Primary support and ssee if that gets rid of the racing sparks. The CD cases are cool because you can stack as many as it takes to see how high you have to raise it before you decide on a permanent fixture.

Arcstarter

Sat Apr 19 2008, 06:38PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

I doubt it but do you have a splice in there? I did that and with sgtc i have major voltage losses due to getting streamers off of the splice.

MOT_man

Sun Apr 20 2008, 02:00AM

Registered Member #1127 Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139

I too had a similar problem with my 3.25" display coil. I had the primary too far up the secondary and racing sparks were a huge issue. So then I took my primary down just so that the last winding of secondary was flush with the top edge of my primary - wow what a difference that made. This was the sweet spot. -- my secondary is tall - 35.5" to be exact. My sparks at 2 kVA are about 2X the length of the coil which is pretty good. On Wednesday this upcoming week I'll be running 2.4 kVA with slightly bigger capacitance. I'm sure I'll hit the high 70's ---- then I'll be running my 6.25" PT powered coil... that will be fun!

H~Tank~V

Sun Apr 20 2008, 03:02AM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

Im still having the same issue it seems, although the racing sparks have seemed to stop.

I raised the secondary up about 1", and there weren't many sparks at all, and if there was any, they weren't consistent.

With a breakout point I get about 10" or so of spark, with no breakout point il get a couple here and there, no more than 10-15".

When I plug in my specs into the spark length eq., it tells me I should have roughly 36" sparks or so, but im not sure how accurate that is.

Now im wondering if something is off or what?

I placed a metal object onto the end of a plastic pole, and it would arc to the object when it was about 5-6" away. Also a fluorescent light bulb lights up from about 6' away too.

Another thing too, I tried the coil out during the day when it was warmer, and I seemed to get allot more breakout from the toroid. Although it was inconsistent, it was alot more than I got at night. Would the temperature effect it at all?

I should be able to have a video up tomorrow

Any other ideas?

Oh and sorry for how jumbled this is, im just thinking and typing!!

Ultra7

Sun Apr 20 2008, 03:17AM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Could it be one of your caps is blown?
Check your solder connections on the MMC.

Also, are your spark gap electrodes burnt up?
Or maybe they are too close?

Another thing to check is your NST.
See if both terminals will pull an arc to the case ground.
As crummy as it sounds, maybe one of your windings is not putting out.

MOT_man

Sun Apr 20 2008, 03:46AM

Registered Member #1127 Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139

Are you running a power factor corrected NST ??? If so you have it likely phased incorrectly... it happened to me once. Very little output.... until I switched the wires around.

J. Aaron Holmes

Sun Apr 20 2008, 04:21AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Glad the racing sparks are gone; it's good to get your TC out of self-destruct mode before worrying about the "finer things" like streamers

Can you post a full rundown of your coil specs? Maybe it's in another thread and I missed it. A video, too, would be interesting.

Cheers,
Aaron, N7OE

H~Tank~V

Sun Apr 20 2008, 12:57PM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

Here is a pic of my NST's spec tag, I dont think it has power factor correction, but im not sure. It does have a built in GFCI though.

Transf

As far as the specs, here they are:

15kV 30mA NST

.01uF MMC (10).1uF Cornell Dubilier 942C

1/4" Tungsten Electrodes about 3/16"-1/4" spacing

10-11 turn Primary, 1/4 copper tubing (tapped at 7-8)

4"Diameter Secondary, 21.5" Long

3 X 12 spun AL toroid

3' X 4' Counterpoise

For the counterpoise, I took a 3 X 4 piece of cardboard and glued AL foil to it. Something makes me think that this could be the issue?

Thanks guys!!!!!! I really hope I can get this thing ripping before my demo on Tuesday!

Thanks again! You guys rock!!!

Ohh and let me know if I missed anything with the specs!

Hazmatt_(The Underdog)

Sun Apr 20 2008, 06:56PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Your system is running fine for 250 VA. If you want 36" sparks you'll need 720VA or more. The spark length calculation you got was wrong. The max spark length I got with 320VA was ~ 18", so you're doing fine.

Matt

H~Tank~V

Sun Apr 20 2008, 07:02PM

Registered Member #1253 Joined: Tue Jan 22 2008, 02:06PM
Location:
Posts: 39

Ok, but I thought i was running 450VA I just multiplied Voltage by Current, I didnt even notice the marking on the trans. Woops.

But even at that, my breakout is really inconsistent. It will discharge a little here and a little there, without the breakout point. With it, it will discharge a decent amoun, but just from the breakout point.

Thanks!

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