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Re: Larger secondary more efficiency?
- To: tesla-at-pupman-dot-com
- Subject: Re: Larger secondary more efficiency?
- From: Terry Fritz <twftesla-at-uswest-dot-net>
- Date: Sun, 08 Oct 2000 22:33:42 -0600
- Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
- In-Reply-To: <001901c031a1$81750740$529d6dcb-at-kellywil>
At 04:31 PM 10/9/2000 +1300, you wrote:
>I need some advice on materials.
>(Living in New Zealand, materials are difficult to find.)
>My power supply is 15kV -at-120mA, and
>I have a large amounts of 24AWG magnet wire
>and 3/16 inch copper refridgeration tubing.
>I would like an 8" or larger secondary, to increase efficiency,
>but over 6 inches PVC pipe becomes too expensive for me.
>I asked around about cardboard tubes equivalent to sonotube,
>(for forming concrete columns) but all I can obtain
>is 300mm OD tube, (that's 11.8 inches). - BTW this is cheap.
I have PVC and Sonotube coils and I like the PVC better. The Sonotube is
really strong but it does get frayed at the edges a little and basically
looks like "cardboard". We also suspect that the Sonotube is very lossy
(if that makes a difference). The PVC coils are rock stable and looks good.
However, larger diameter secondaries have higher coupling. In this case it
is about .12 with the 6 inch and 0.2 with the 12 inch secondary.
>With 120 mA of current, can I use that large a secondary?
>(It's all I can get )
>I have heard that larger coils are more efficient, but surely
>there is a cut off point where efficiency starts to drop as coil forms
15kV at 120mA implies a 1.8kVA coil which should put out streamers about 72
inches long. So a 30 to 36 inch secondary would be fine. I like longer
secondaries to reduce racing arcs and primary strikes. I would think the 6
inch dia. would be good but you may want a conical primary to help
coupling. The 12 inch may have to be rasied a bit if racing arcs appear.
If you close wind, count on having about 15-20 primary turns but run the
numbers through one of the programs to check on all that.
>Thanks in advance,