RE: NST Shunt Removal (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 14 Jun 2007 10:06:40 -0400
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: NST Shunt Removal (fwd)

Hi Bart:

I'm still kicking myself for not taking photos of my NST before I
repotted it.  I think I was so disgusted with how messy the process was,
it wasn't something I wanted to remember.  It also pre-dated my digital
camera and I just wanted to get it done.

My recollection of the core construction is dim, as at that time I had
never seen a core that HAD removable shunts.  I know that I would have
recognized something that would have been removable.  I don't think the
shunts were welded, as I was able to completely disassemble the core
from the windings without difficulty.  I believe the shunts were
integral to the main laminations, rather than being separate
laminations.  I think there was a pre-set air gap in the shunts between
the two core sides.  I've seen a similar construction on small
open-frame NST's and bug zapper xfmrs.  It may be possible to drill a
hole through the integral shunt to reduce the cross-section area of
metal.  But then you'd never be able to dis- and re-assemble it, and if
you drill out too much metal, there's no going back.

Regards, Gary Lau
MA, USA

> ---------- Forwarded message ----------
> Date: Tue, 12 Jun 2007 20:26:00 -0700
> From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: NST Shunt Removal (fwd)
> 
> Hi Gary,
> 
> I've never dissected a Jefferson. How are the shunts not removable?
Did
> they weld them in place? If so, could the weld be grinded off to free
> them? Weld grinding is one of those areas I've unfortunately had to
deal
> with, but in every case, the weld can be ground away quickly.
> 
> Take care,
> Bart
> 
> Tesla list wrote:
> 
> >---------- Forwarded message ----------
> >Date: Tue, 12 Jun 2007 20:17:42 -0400
> >From: "Lau, Gary" <Gary.Lau@xxxxxx>
> >To: Tesla list <tesla@xxxxxxxxxx>
> >Subject: RE: NST Shunt Removal (fwd)
> >
> >It may just be me, but I think an oil-immersed NST is a mess waiting
to happen.
> Oil-filled containers, in particular plastic ones, simply WILL leak.
> >
> >When I unpotted my 15/60, I simply re-used the original metal case.
You'll not
> find a better fitting alternative.  Yes, it is not oil-tight.  So I
filled it not with oil but
> melted Vaseline jelly.  After cooling and solidifying, it's leak-proof
and spill-proof,
> and not a lick of trouble since.
> >
> >BTW, my 15/60 was a Jefferson, and its core construction does not
lend itself to
> shunt removal.
> >
> >BBTW, the Vaseline jelly might melt somewhat if one were to operate a
deshunted
> NST for many consecutive minutes.
> >
> >Regards, Gary Lau
> >MA, USA