Re: High Voltage Potting

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

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

Steve: I did not see another posting so I will make some comments. A double
boiler is a cooking pot with water in the bottem and the matter to be heated
without scorching is in the top. Oil can be used in the lower part if higher
heat is neaded. It is a pan in a pan.
  Parafin wax ( petrolium product) is good, but you must use a small excess
as it contracts as it cools. Heat-Glue works even better.
   I have not used ABS. I suspect it will work.
    Heat glue remains flexable at most tempratures while wax gets solid and
will crack when cold or it will run like water when hot. Heat glue dosen't
melt to a liquid at low temprature.
  I hope this helps   Robert  H

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Wed, 01 May 2002 08:05:08 -0600
> To: tesla-at-pupman-dot-com
> Subject: High Voltage Potting
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Wed, 1 May 2002 08:14:08 -0600
> 
> Original poster: "Steve Burgess by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <SBURGESS-at-Channel4.co.uk>
> 
> Hi Guys
> 
> I was interested to read your thoughts on HV potting:
> 
> http://www.pupman-dot-com/listarchives/2000/July/msg00931.html
> 
> I need to build a replacement tripler (voltage multiplier in the manner of
> Cockcroft-Walton) for a failed unit in a high quality 16x9 aspect ratio
> (widescreen) television monitor I have.  It will use 6 HV diodes (eg BY8418)
> and 5 1000pF/15kV caps - plus 15 HV resistors connected in series to bleed
> 100 microamps from the 28kV EHT output which goes to the CRT's final anode.
> This bleed current is fed back to stabilise the 28kV (and thus picture size)
> against variations in beam current.
> 
> I plan to pot in a 100 x 50 x 25mm ABS plastic potting box and will use a
> couple of small polypropylene sheets to string the diodes and resistors
> between, with the caps on the outside.  I'll pot flying wires for the
> ground, first-stage focus volts take-off, the EHT out and the bleed current
> - and a pin to take the 9.5kV input pulse wire from the step-up transformer.
> 
> I knocked-up a 'free-air' doubler recently which gave 20kV - and the odd
> spark and bang, so the need for encapsulation obvious!
> 
> Maybe you can answer some questions for me:
> 
> Which type of wax should I use?
> What's a double boiler?
> Is ABS plastic OK with the wax-and-polyethylene-strip mix at pouring
> temperature?
> Is the mix good for not fracturing with movement at wire lead-outs?
> How good is the method at eliminating air (to avoid corona)?
> Latest tips?
> 
> Hope you can help.
> 
> Thanks
> 
> Steve Burgess
> London, England
> 
> 
> 
> 
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