Re: fFINAL REPORT Cu COIL vs Al COIL (fwd)

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Date: Thu, 11 Oct 2007 17:39:32 -0700
From: Ed Phillips <evp@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: fFINAL REPORT Cu COIL vs Al COIL (fwd)

Ed mentioned in one of the posts today that aluminum should be fine if a 
larger diameter is used and he's absolutely correct. If you increase the 
diameter of aluminum accordingly, you have an equivalent copper 
conductor. In the primary coil, this is doable, but on the secondary, 
the geometry and turns would be effected far more and may not be the 
best thing to do (irregardless of losses). Both mechanical and 
electrical to deal with in the secondary. You can of course ignore the 
mechanical and just wind the same size with Al. The problem then is ACR 
and DCR increases. Maybe a couple inch difference in spark length, but 
even that is not a big deal (IMHO).

The main point in all of this testing is that "material directly affects 
the coil by it's permeability". There is a difference between aluminum, 
copper, or any other material used. Radio frequencies affect losses, but 
it can be dealt with when using non-ferromagnetic materials and 
certainly becomes a problem if using ferromagnetic materials.

To say that aluminum is bad for RF is not an intelligent statement. It 
depends on the application (frequency, conductor size, shape, and current).

Take care,
Bart"

	I should mention that all of my thoughts concerned primaries.  I can't imagine any good reason for winding the secondary with aluminum, even if it were possible to find suitable wire.  Copper is fine and probably at least as cheap as insulated aluminum.

Ed