Re: compact oil insulated secondaries?

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 08:06 AM 4/23/2003 -0600, you wrote:
>Original poster: "Jolyon Vater Cox by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>
>Dear List,
>I am considering building an oil filled secondary
>to improve durability and increase compactness in a small TC in which I am 
>currently using a secondary of 880t of 32swg enamelled copper wire wound 
>on a former measuring 10.875" long x 2.98 diameter.
>
>My reason for doing this is because I am planning to double the number of 
>turns by winding a new secondary using 40swg wire on the same former
>and there may be insulation issues to be considered here.
>
>What is envisaged here is a double-walled cylinder made from two 
>plastic  tubes of dissimilar diameter the winding wound on the smaller 
>inner tube with the oil contained between this and the larger outer tube.
>the ends of the tubes plugged with rings cut from a polythene chopping 
>board and sealed with silicone.
>
>I am anticipating cutting the rings from the board using a  hole saw 
>driven by an electric drill with cutting blades of different diameters- 
>will this be OK?

This works fairly well, but the cut isn't always the smoothest in the 
world, and the "as cut" sizes available may not nicely nest.  Silicone 
doesn't stick all that well to PE (nothing does!). You might want to 
contemplate some other material.

One of those circle cutters that has a single point on a bar that sticks 
out from the middle will make a smoother cut, and you can move the cutting 
point in inifinitely small steps.

Some sort of jig or stand to make sure the cuts are perfectly perpendicular 
will help a whole lot.





>Has this method of construction been tried before and  is 
>containment/leakage of the the oil likely to be a major problem?
>
>More importantly, what is effect of the oil on primary-to-secondary 
>capacitance -are there tuning issues to be considered with this?
>
>Jolyon