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Re: Secondary


TE>From richard.quick-at-slug-dot-org Sat Sep 30 09:12 MDT 1995

TE>Quoting jbiehler-at-teleport-dot-com (Jerry Biehler):

TE>> I got the 8" PVC today. Cost me $7.00 for 3 feet. It is solid wall
TE>> about 5/16" thick. I am going to setup something to dry it later today.
TE>> I got a basic polyurethane varnish to coat it with.

TE>No problems here.

TE>Holes in the coil form are avoided primarily because holes compromise
TE>the electrical strength of the construction. The fact that a properly
TE>sealed and capped secondary coil prevents re-absorbtion of moisture
TE>when using properly dried and prepared PVC is an added bonus. Desiccants
TE>such as calcium sulfate, silica gel, etc. will simply trap water. I
TE>would not use these desiccants with the idea that these materials are
TE>going to end up as permanent parts of the coil. Desiccants can be em-
TE>ployed as part of the drying process if desired, but these compounds
TE>should be removed (with the absorbed moisture) and not left as part of
TE>the sealed construction.

Richard has also talked elsewhere about the importance of sealing
the inside of the coil form. This is the reason I dip my coils
totally into a hot wax melted especially for the purpose. Richard
Hull does not always coat his secondaries. In our climate the
coil and former soon becomes "damp" and the performance
decreases, all the other components are affected by this as well.

Jim Oliver <jim.oliver-at-welcom.gen.nz> (3:771/370)

 * SLMR 2.1a *