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What to look for in an old NST

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HM_Murdock

Fri Aug 20 2010, 02:11PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

I have the opportinity to pick up an NST from a local sign shop...the owner says they have "several" of the older steel core ones laying around, and I can come get one.

For all around general purposes, what should I look for on these to get one that will work for HV projects? Looking for something that will give nice results, but nothing gigantic...

Heading over there in a couple of hours...hoping to get some feedback first.

Thanks!

Jiffycoil

Fri Aug 20 2010, 02:28PM

Registered Member #2524 Joined: Wed Dec 09 2009, 06:29AM
Location: Johns Island, South Carolina
Posts: 23

Free is always the best NST. Old NST's are great. No GFI of course. Insulators are in good condition. 12kV-15kV 30mA, 60mA is better. When its plugged in it doesn't make a loud buzz sound. If someone will give you free NST take as many as they will give you.

quicksilver

Fri Aug 20 2010, 02:33PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

MANY are potted. Thus getting a quality name is the 1st place I would start.
Franceformer
Magnodynamics
Most anything made in Canada or the States would be fine. There re a lot that are available in a "white box" that are heavily potted in a tar-like material (they may be made in Thailand; not sure....) but they really cannot be altered - the potting is too much trouble. They function fine from what I've seen.
The tough ones to find are on the ends of the scale....Either something with 60ma or greater (tough to find) or light-weight 7k w/ 20ma. Those on the far end of the range are tough to find. Finding a decent France-former at 12-15k at 30Ma is common and a very workable unit that lasts a lifetime if not abused.
BUT....free is free. If you get a white-box unit and she works: be happy and have good time; juice is juice.

HM_Murdock

Fri Aug 20 2010, 02:34PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

I will take all the free I can get (much to my wife's dismay...lol).

I just wanted to know what to look for when he says "sure, pick one of these" in order to get a good one...

I know to get one without the protection circuit built in (though I am unsure how to discern this detail by looking at it, other than it would be much lighter in comparison to an older one maybe?)

quicksilver

Fri Aug 20 2010, 02:38PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Look for where it's made! But IF he really wants to hang on to the good stuff; be grateful you got a free-anything.
France-former is generally the classic Magnaton, etc all good. LOOK at the QUALITY of the total constriction and insulators. If it's a cheapo, they don't put money into ceramic insulators.

Jiffycoil

Fri Aug 20 2010, 02:38PM

Registered Member #2524 Joined: Wed Dec 09 2009, 06:29AM
Location: Johns Island, South Carolina
Posts: 23

Most NST with GFI will say so on the label.

HM_Murdock

Fri Aug 20 2010, 02:45PM

Registered Member #3075 Joined: Fri Aug 06 2010, 02:44PM
Location: Athens, GA
Posts: 148

Don't misunderstand me...if he says "here, you can have this one, I don't even know if it works, but it's yours", I will thank him profusely and be happy I got it at all!! I offered money, and he said, "Nah, we got 15 or 20 of those old things laying around...just go see Joe, tell him I said you could have one"

Just wanted to know what to look for IF I had a choice in the matter...like to be informed when I can, ya know?

Thanks!

Xplorer

Fri Aug 20 2010, 02:48PM

Registered Member #2416 Joined: Sun Oct 04 2009, 04:23AM
Location: Oceanside, CA
Posts: 91

Ask them to test it for you, if they're willing. If you can draw and arc then they don't have a GFI.

I bought my first NST form a local sign chop. It was a 9/30, I think I paid 30 bucks for it.

-Tony

radiotech

Fri Aug 20 2010, 04:21PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

I will take all the free I can get (much to my wife's dismay...lol).

Years ago the college I was working for offered a roomfool of electronics gear providing I took it all.
It included a large stack of vaccum tube taxi 2 way radios. A friend picked them up at my place later on. His wife almost threw him out
and she didn't talk to me for ages after.

HV Enthusiast

Fri Aug 20 2010, 05:15PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

4kV/20mA and 6kV/20ma or 6kV/30ma sizes are great for small tabletop coils.

12kv/30ma and 15kv/30ma great for mid-size coils.

and 12kv/60ma and 15kva/60ma are the largest ones most commonly found. If you can get these sizes, that would be great.

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