RE: a few questions about secondary construction

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Original poster: "Ted Rosenberg by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>

Hi Bill: Let me address a few odds and ends of your post.
For that level of input 'I' think you can use an 8" thin wall. The support
will come from the end pieces.

I used 24 wire and I will use that also on the 8" I plan...15/180.

I mounted a RadioShack PL-259 surface mount terminal on a 2" PVC end plug.
The end plug is cemented to the bottom disk. My RFG connection is a #4 cable
that screws into the PL-259. Very hefty and able to handle the current. Plus
convenient to setup.

The toroid mount is fabricated from a CB Rooftop Antenna Bullet. It's also
an RS item, 21-1116 on pg 96 of the 2001 catalog. It mounts on the upper
disk and the torroid mounts to it. Sturdy and convenient too.

Finally, the outer coating...I gave up on poly. I now use an epoxy from Tapp
Plastics. Their general epoxy is reasonable (less than what you stated). The
only shortcoming is that it sets up quickly. I would spread it with a 12"
windows squeegee for speed and accuracy.

All of these will be detailed in my soon-to-be web site that tells and shows
all.

Hope this helps in the meantime.

Safety First

Ted

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, November 02, 2001 1:27 PM
To: tesla-at-pupman-dot-com
Subject: a few questions about secondary construction


Original poster: "Bill Vanyo by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<vanyo-at-echoes-dot-net>

I just got my 9" by 30" spun aluminum toroid, and am considering
rebuilding my coil to do it justice.  My current coil (dead by capacitor
failure) has a 6.5" by 27.5" secondary, 1000 turns of 22 awg, and is
powered by three 15/60 NST's (and has a static gap).  I'm adding a
fourth 15/60 (for a total of 15kv/240ma).

I'm planning on winding another secondary, and here are some of the
changes I'm considering.  I'd appreciate any feedback on these points.

1) Diameter: Would it be better to have an 8" diameter secondary, as
opposed to my current 6.5"?  Perhaps even 10"???  (the primary will, of
course, be adjusted accordingly)

2) Thick vs. thin walled PVC:  My current secondary is wound on thick
walled PVC.  I've read that thin wall is better.  Is there really that
big of a difference?  The new toroid is rather heavy, and it just seems
like something solid would be better.

3) Ground connection: I currently have a flat copper ground plate at the
bottom of the coil (for the most part, I followed guidelines on this
page: http://privat.schlund.de/s/skluge/coilbld.htm ), but am thinking
about using a nut and bolt type terminal connection, possibly mounted
through the wall of the pipe (below the bottom end cap).  With the flat
plate, I'm not sure how to make a solid connection (early on, I made the
obvious mistake of using a pipe clamp - a shorted turn that did some
heat damage to the polyurethane).  Would a bolt through the wall, just
below the botton end plate, be OK?

4) end caps, toroid mount: My end caps currently consist of a sandwich
of 3/4" plywood epoxied between two layers of some unknown type of hard
white plastic I had laying around.  The top cap has a 3/8" bolt through
the top layer of plastic.  I want to do something similar - a mounting
bolt on top, to which the top end of the coil wire is permanently
connected.  What I need is a reasonably priced source of the right kind
of plastic.  Some of the online plastics catalogs seem to be
exorbitantly priced, even for just enough to fashion a couple of end
caps.

5) epoxy: I used polyurethane the first time - many coats, applied and
dried while turning on the winding jig - and the results were beatiful,
but I want something more rugged (hence also why I'd like to go with the
thick wall PVC).  I was looking at an epoxy at
http://www.epoxies-dot-com/tech/20-3302.htm , for which they quoted me a
price of $45/qt resin, 17.50/pt catalyst (2:1 ratio), which I think is
enough if I'm careful.  Does it get a lot cheaper than that?  Can anyone
recommend a good alternative epoxy available online? 


	Thanks,
	Bill Vanyo