Re: TC Primary

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ottalini-at-mindspring-dot-com>

Mark:
        You can use your browser to view ftp sites as well.  You can pic up
the link
through my minimal web page (I don't have the web page done yet):

http://www.mindspring-dot-com/~ottalini/

and click on the "mindspring FTP" link.  There are many pictures and TC
related
files there that you are welcome to browse through.  I will eventually
migrate
most of this to the web page (in my not-so-copious free time).

If you still can't get the pics, let me know and I'll migrate the primary
related
ones now.

I'm using HDPE or high density polyethylene plastic for my supports which
cuts
and drills and taps quite well. HDPE is relatively inexpensive and available
generally at any hardware store in the kitchen utensils section as "cutting
board".

Many plastics specialties stores sell HDPE also and will cut it for you for
a small
fee.  HDPE cuts well on a table saw, but you need to be very careful with
small
pieces since the blade can grab them and fling them across the room, or at
you
or up into the overhead fluorescent light fixture as it happened with me
(glass went everywhere!).

A good alternative often used for TC work is phenolic, which is a resin and
canvas or linen laminate.  It seems to be more expensive new, but is often
available surplus.  I also tried a thick polycarbonate piece which works,
but is too expensive.

If you have trouble cutting a narrow enough slot, an alternative is to use a
thin strip of polycarbonate (or whatever) as a spacer or shim next to the
copper. This can be a parallel strip that winds with the copper flashing.

I used a small band-saw to cut the first primary, but the blade has an
unfortunate tendency to walk so the slots are all at a slight angle.  A
hack-saw blade or a good miter saw with the smallest tooth pitch is
much better, but takes a little more elbow grease.

I also found that putting a thin strip of foam (tape or otherwise) under the
top piece helps significantly to hold the copper in place.

I usually cut the slots 1/4" apart.  On the new 2" primary, I skipped every
other
slot so the spacing is 1/2".  1/4" is the minimal spacing that I could
reliably
hold with the copper (and keep them from touching around the bends), and
also allow enough room for the clip I use for the primary tap.  The issue
with
the spacing isn't when the primary is new, but later as it gets moved around
and bent a bit from handling, etc.

The thinnest, reliable clip I could find that could handle the current is
sold by
Radio Shack as a "stainless pager belt clip" for a few dollars.  I take an
extra
piece of he copper sheeting and fold it over and then slide the stainless
clip
over the outside of that piece.  You then slide the clip up onto the primary
wherever you want,  and the folded over copper make a fine double-sided
connection.

The cable to the spark gap is attached to the copper, not the clip itself.

I hope this helps!

ko

----- Original Message -----
From: "Mark W. Stolz" <mark_w_stolz-at-hotmail-dot-com>
To: <ottalini-at-mindspring-dot-com>
Sent: Friday, June 22, 2001 6:30 AM
Subject: TC Primary


> Kevin,
>
> I'm preparing to build a new primary using the flat copper ribbon like you
> have and I had a couple questions for you.  What are you using for
supports
> for the ribbon and what spacing do you use turn to turn?  One more
question,
> what is the URL to your website?  The links you posted to the list were
FTP
> links as opposed to HTML.  Thanks for any help you can give!
>
> Mark
>