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Re: repair
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To: tesla@pupman.com
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Subject: Re: repair
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From: RODERICK MAXWELL <major@vicksburg.com>
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Date: Sun, 02 Feb 1997 15:40:30 -0600
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Subscriber: major@vicksburg.com Sun Feb 2 17:45:59 1997
Tesla List wrote:
>
> > > > > Subject: Re: repair
> > Subject: Re: repair
>
> Subscriber: bert.hickman@aquila.com Sat Feb 1 21:51:51 1997
> Date: Sat, 01 Feb 1997 09:08:05 -0800
> From: Bert Hickman <bert.hickman@aquila.com>
> To: tesla@pupman.com
> Subject: Re: repair
>
> Tesla List wrote:
> >
> > > > > Subject: Re: repair
> >
> > Subscriber: major@vicksburg.com Fri Jan 31 23:12:03 1997
> > Date: Fri, 31 Jan 1997 23:38:56 -0600
> > From: RODERICK MAXWELL <major@vicksburg.com>
> > To: Tesla List <tesla@poodle.pupman.com>
> > Subject: Re: repair
> >
> <SNIP>
> >
> > I just unpotted the first of four neon transformers that I got from a
> > sign shop in town. The guy there told me they were 15Kv @30ma. I'm sure
> > they are 15Kv but not so sure about the current rating as the plates
> > have all been removed. I kind of went back to the dark ages in the way I
> > removed the potting. I boiled them in oil! I used a burner out of a old
> > space heater to heat the metal pan pan filled with diesel! I know this
> > sounds dangerous folks but it was a good 20' away from anything that
> > would burn including yours truly. It really speeds up the process as it
> > uses solvent and heat to disolve the tar. Just don't try this at home
> > folks! The core looks, and disassembles the same way discribed in the
> > archives. One secondary reads megohm resistance and is probably fried.
> > The other reads a little over 8kohms. Is this the usual resistance of a
> > 15kv secondary? Or is this side shorted???
> >
> > Frankensteins Helper
> > Max
>
> Roderick,
>
> Wow - you must like to live dangerously! :^) Then, I guess coiling
> itself is not completely without risk either...
>
> Anyways... The resistance of a neon secondary should be measured with an
> analog VOM. Digital meters tend to get "confused" when presented with
> all the inductance in the secondary. The DC resistance of a secondary
> winding will vary by manufacturer and model. Also, some manufacturers
> have switched to aluminum wire to save weight and cost - these will run
> higher DC resistance than for copper wire.
>
> In general, 60 MA transformers will have significantly lower DC
> resistance than the 30 MA ones, irrespective of output voltage. This may
> imply that they can be "pushed" further (by running at 60 Hz resonance
> with the tank cap, or by removing some shunt plates). Below are some
> typical DC resistance measurements when going from a HV bushing to the
> center-tap ground. Bushing-to-bushing values will be twice those below.
> Also, your mileage may vary. :^)
>
>
> Voltage MA DC Ohms (HV bushing to Center-Tap)
> ======= == =============
> 9000 30 11,000-13,000 (mini-size)
> 12000 30 9,000-11,000
> 15000 30 8,000-10,000
>
> 9000 60 2,400-2,500
> 12000 60 2,400-2,700
> 15000 60 2,000-3,000
>
> Hope this helps, and safe de-potting to you!
>
> -- Bert H. --
Thanks for the resitance values. This will help in identifying
transformers that have had their plates removed.
Frankensteins Helper
Max