Quote:
Originally Posted by Travellingwave
My other thought was that the failures might occur at either end of the bobbin , where the paper has probably disintegrated over the years. This might explain why in situ revarnishing might have worked for others , I struggle to believe that any varnish could penetrate very deep into the windings unless it was done under vacuum.
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Yes, vacuum seems the best way to do it.
All I can say is that dipping the lopt in varnish (marine spar, transformer or anti-corona) while still wet from the white spirits and leaving it overnight in the varnish (the first and most important dip) seems to do the trick, i.e., no failures in the primary and no corona discharges in the overwind, unlike my first lopt which was left untouched and died on the second day after some 3-4 hours of apparently perfect operation. If my varnished lopt ever dies, I will make sure to post it on the forum.