RE: I wonder ...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Garry Freemyer by way of Terry Fritz <twftesla-at-qwest-dot-net>" <garry-at-ndfc-dot-com>

Hi Alan. Well you may disagree but my experience with the 12/60 Jefferson
was QUITE different than yours and I am not alone in this experience. No
offense taken or intended, but I don't lie.

I think Terry was one who had difficulty with a Jefferson. Whoever the two
people who mentioned bad experiences with Jefferson's please speak up! There
was one who said the layers were tarpaper and also were disolved along with
the tar. Mine is completely ruined because half of the paper on one side was
completely disolved away leaving a birdnest of ruined windings. The tar
resisted desolving like mad. I put the thing in an oven and I set the
temperature to 200 degrees. After 45 minutes, the tar was still hard as a
rock. I increased it to 250. Another hour and the tar looked shiney but hard
as a rock. I increased to 300 for 30 minutes and it still pretty hard. I set
it to 350 for another  hour and it was just softened a little. I ended up
setting it up to 425 or so before the tar began to start running. I finally
got a good portion of the tar out and then I plugged it in to see what was
up and I immediately got sparks from the windings to the case. The area
between the case and the windings had no insulation. There was NO tar and
never was any tar between the windings and the case as the area of the case
was clean as driven snow and I would think that if there were ever tar
there, it would be left on the inner side of the case.

I soaked the thing in mineral spirits for two weeks and then looked at it.
Only the outside surface of the tar had softened and it was protecting the
inner surface. There were large parts of the tar that were had as stone. A
month or two later I looked at the unit and the condition was much the same
with large stone like portions of tar covered in a whitish substance.
Contrast this with the two Allansons I depotted. They were virtually clean
in a month of soaking. I soaked this unit from Mid November till the last
week in April and the tar was finally softened enough to remove with a brush
but the tar had a fiberous stringy consistancy as if it were full of sewing
thread. I carefully brushed off the unit under the tar and removed it and
here was half the secondary insulation eaten away leaving the windings
sticking out in space.

I'm not particularly concerned about removing shunts. I get quite
satisfactory performance with the allanson I depotted and besides, its too
loud already! ;-)

I guess, all I can do is calmly say, that your experience doesn't even
remotely jive with mine and a couple others on the list. I don't doubt what
you relate. I'm just a little mystified as to why your experience can be so
different than mine. The only difference I can see is you used a BBQ and Gas
and depotted two quite successfully and I used an Oven and mineral spirits
and I only depotted one. Perhaps it was the extended soaking I gave the unit
that finally even broke down the paper? How long did you have to soak them
in Gasoline? How hot do you estimate you had to get the tar to melt? A bbq
sounds like it could easily get to over 400 degrees.

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, May 30, 2001 8:12 AM
To: tesla-at-pupman-dot-com
Subject: Re: I wonder ...


Original poster: "Alan Yang by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<megavolt121-at-mediaone-dot-net>

Gary, All
The list of bad caps is on the list. Unless a lot of people have it on their
sites, most people wouldn't see it.

I totally disagree on you on the topic of depotted Jefferson's though. Ive
depotted two of them brefore. They weren't that bad at all. It was simple to
unpot. Just turn it over and put int on a pan. then stick it in my BBQ and
let it cook. the core falls out, i soak it in gas, then clean and its ready
for deshunting. This is the only pain for you have to cut them out. Its
easier now that i have good cutting tools. I believe two people on this list
have my depotted nsts which i gave away and last time i heard, both were
happy with their nst's and say they ran nicely.

-alan

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, May 29, 2001 7:49 PM
Subject: I wonder ...


> Original poster: "Garry F. by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<garryfre-at-pacbell-dot-net>
>
> Some poor fella send me email about how he was in the process of depotting
a
> Magetek's Jefferson NST.
>
> I remember these horrible things. The one I had, did not have tar between
> the case and the secondary which was only an 8th of an inch away!
>
> The windings on both sides literally melted. I tried to depot the thing
and
> as someone else also observed, the windings are insulated by tarpaper and
> anything that will melt or disolve the tar, also disolves or ruins the
> tarpaper.
>
> The poor fella had already started soaking it.
>
> I suggested he remove the thing and try to restore the connections and
just
> put the thing, tar and all into a container full of mineral oil.
>
> The core and shunts are also one piece. There are no separate shunts that
> can be knocked out.
>
> The silicone also raises the melting point of the tar to above 400 degrees
> in my experience.
>
> The thing I am wondering about is we have a list of known bad caps.
Perhaps
> it would be good to add a section of parts to avoid where people could be

> warned away from buying this brand of NST if they are planning to depot
it.
>
>
>
>
>