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Re: High frequency impedance of a neon sign transformer


Ed,

The impedance of the secondary of a neon sign transformer is tremendous at 
any frequency!   Even if we took the laminations out the secondary, the air 
core inductance of several thousand turns of 38 gauge wire in a fist sized 
ball would be the best portion of a henry or two and at 500khz,  that is 
still about 3 megohms.  Neon transformers are doomed in Tesla service!  Long 
run times and wide gap openings kill this transformers very quickly.  I 
should know, I've killed more of 'em than many pople have ever even seen in 
a life time.  With very small gap openings and light use, I have had 
transfomrers last 2 or 3 years in some applications.
 ---------
From: tesla
Ed Phillips EP wrote:

Hi Ed,

EP>Ed:
EP>     I am very interested in your measurements of neon secondary
EP>impedance as a function of frequency.  One question, though.  Don't
EP>you really mean that the high-frequency impedance is CAPACITIVE?
EP>Inductive reactance wouldn't decrease with frequency like that.

<--snip-->

Thanks for the interest. I think its something that may need a bit
of looking into. Now for your question:

It dosn't appear to be capacitive since the measurement shows that
the time dependent voltage leads the current by about 90 degrees no
matter what frequency is used. If I understand you concern correctly,
you're saying that in a pure inductance the impedance always goes up
with frequency, right? So why does my measurement show an inductive
impedance which goes down with frequency - is that it?

The two effects which are probably important
were in the initial post:
        Also, I was hoping that someone else would try the measurements
so that we could compare results.


 -Ed Harris