Re: Flat Ribbon Conductors


Aluminum is a very bad RF conductor in general.  It forms a deep resistive
oxide layer on the surface that plays havoc with skin depth adding greatly
to the primary resistance and losses.  Wide straps helps to make up for
this.  Avoid magnetic materials completely.  Brass and copper are best.  I
don't think silver or gold plating will help considering the other losses
in the system although they may help in a corrosive environment and gold
would look great ;-)).  Having said that, it is fairly complex to determine
if adding a ohm or so to the primary circuit will hurt a given coil's
performance noticeably.  In a high energy well tuned coil, it could make a
big difference.  In another coil it may not be noticeable.  "I" would avoid
aluminum completely.  However, if you have a bunch around, you will
probably be happy with the results especially if you don't have a copper
primary right there to compare it with.



At 01:16 PM 05/05/2000 -0700, you wrote:
>-----Original Message-----
>From: Tesla List <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
>Date: Friday, May 05, 2000 1:04 PM
>Subject: Re: Flat Ribbon Conductors
>>Original Poster: Hollmike-at-aol-dot-com
>>In a message dated 5/5/2000 8:27:39 AM Mountain Daylight Time,
>>tesla-at-pupman-dot-com writes:
>>> I've personally not tried aluminum but others with more experience have
>>>  pointed out that aluminum has a very high resistance oxide coating that
>>>  makes its resistance at RF frequencies undesirable.  Others still have
>>>  it and it worked, but probably not as well as any good copper primary.
>>If one wished to go to the trouble, aluminum can be strike plated with
>>and then silver plated.  This would fix the high resistance problem.  On
>>other hand, I have seen a primary made from the aluminum flashing thaat
>>worked as well as any coils I have seen.
>>   Mike
>Given the fairly thick skin depth for tesla coil frequencies, I don't know
>that a thin silver plating would help much, and nickel isn't all that great
>as a conductor (it's used as resistance wire, for instance).. conducts just
>enough to be lossy. Also, it is magnetic, which would probably have all
>sorts of horrible effects on the skin depth thing, because skin depth
>depends on both permeability and conductivity.
>   Aluminum has about 60% of the conductivity of copper, so just make your
>aluminum component twice the diameter/width/thickness/etc, and you'll be
>ahead of the game.