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Re: Secondary


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

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

No problems here.

> You said you did not want to put any holes on the coil form if
> necessary because of moisture seeping in. What about throwing a couple
> packets of silica gel in before sealing it up? Or maybe some other
> dessicant? 

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

> Oh, how did you cut the plexiglas disks in a circle? 

I use a band saw or a jig saw. A plastics dealer will be able to custom
cut these disks if required, and the same plastics dealer is usually 
able to supply the correct blades and cutting advice if you ask.

> And what about using a Silicon RTV type cement to attach the ends. This 
> stuff is deffinitly non-flamable and is hard to screw-up with.

Good Question!

Sounds great does it not? But... These adhesives leave a residual acetic
acid vapor which is trapped in the coil form. The acetic acid is highly
conductive and ionizes readily. Don't use these products in this par-
ticular application.

> I am also going to order the wire today. What gauge should I use?

I would used about 888 turns of number 22 AWG enameled magnet wire.
You will need about 3.75 pounds of wire to complete this project, so,
figure on buying four pounds of No. 22 AWG enamel covered magnet wire.

Richard Quick


... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12