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Re: Using guts from BTC-3

Subject:  Re: Using guts from BTC-3
  Date:   Mon, 28 Apr 1997 20:43:41 -0500
  From:   "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
    To:   Tesla List <tesla-at-pupman-dot-com>

 
> 
> Howdy coilers,
>         Like some coilers, my first TC was the BTC-3 from Information
> Unlimited. It wasn't unitl I got on the Tesla lists that I discovered
> how poor design the kit was. The primary setup was funky because it
> had a number of turns of PVC covered stranded wire bunched together
> and soldered to a 3 turn solid piece of wire where tuning occured.
> I am sure the bunched coated wire was just there to provide enough
> inductance to bring the system close to tune. The kit was an okay
> learning experience but I found almost every aspect and component 
> lacking good efficiency. When I changed all the components, I actually
> ended up with a totally new coil from scratch that used absolutely
> no parts from the kit! 2 components from the kit are acceptable keepers.
> The 6kv-at-23ma open core transformer and the .005uf -at- 6kv capacitor.
> The secondary is toast as it has an internal grooved arc highway
> due to the fact that they (Information Unlimited) drilled holes in the
> side of the form. My end thought is that Inforamtion Unlimited wanted
> maximum money for the kit with minimum money spent for parts.
> 
> I want to take the lonesome transformer and cap and make a small
> table top coil I can take with me to show people. 
> 
> I have everything worked out in my mind except for one aspect.
> Because the power output from this transformer is low, I will
> choose the inverted cone primary. I know for surface area that
> it is good to use the copper tubing but I really don't want to
> make this system big and am thinking of a samller primary than
> using copper tubing, even the 3/16" stuff.
> 
> [snip here]
> 
> QUESTION:
> 
> Do you think it is possible to get good results with this
> small system if I use the bare copper wire that is sold
> for ground connections to circuit breaker boxes?
> 
> I know it is not tubing and that its surface area is smaller
> and a waste that it is solid, but it seems to me that I can
> have a much physically smaller primary.
> 
> One recourse: I can use the copper tubing and just have say
> 4 turns, make my primary first, and wind the secondary to
> be within tuning range.
> 
> 
> Thanks,
> 
> Bob Schumann
> 
> tesla-at-america-dot-com
> http://www.america-dot-com/~tesla
> 
> 
Bob,

For a small coil like this you can get great results using just #14 AWG 
PVC copper solid wire wound on a shallow, large diameter cylindrical 
(solenoidal) form.  For example, wind about 20 turns near the end of 
a 5 gallon plastic bucket.  While winding you can strip 2 inches of 
insulation at a point once per turn and twist it with pliers to give 
you a connection point for a tuning tap.  Put a tap on every turn of 
the last 10 turns.  A secondary wound on a 4.25 inch diameter PVC 
pipe form anywhere from 14 to 24 inches long will be excited perfectly
with
this diameter primary.

rwstephens