Re: Poor Form? (fwd)

To: tesla-at-pupman-dot-com
Subject: Re: Poor Form? (fwd)
From: Tesla List <mod1-at-pupman-dot-com>
Date: Sat, 14 Feb 1998 08:38:03 -0700 (MST)
Approved: mod1-at-pupman-dot-com


---------- Forwarded message ----------
Date: Fri, 13 Feb 1998 23:44:56 -0500 (EST)
From: richard hull <rhull-at-richmond.infi-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Poor Form? (fwd)

At 10:16 PM 2/12/98 -0700, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Thu, 12 Feb 1998 11:07:30 +0000
>From: "Gregory R. Hunter" <ghunter-at-mail.enterprise-dot-net>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Poor Form?
>
>Dear Folks,
>
>Thanks for answering my query about sonotube.  I've seen it before
>at construction sites, I just didn't know it was called "sonotube".
>
>One writer has suggested that this may be a poor choice of coil
>form. Is cardboard tube lossy or something?  For low RF losses, I
>would think well-sealed cardboard would be nearly as good as air, and
>superior to PVC.
>
>Greg
>
>Dreaming of Megavolts in East Anglia, UK
>
>
Some folks claim OK results with cardboard.  I have measured Q's of unsealed
cardboard resonators and found them the worst of all form materials tested.
PERIOD!!  We did a complete series of tests on one of our video report tapes.

  With small coils you will not really lose all that much.  Wood forms
turned out to be the second worst form material.  PVC turned out to be
rather good!  The best is styrene, Teflon, or the ultimate would be a
polyethylene storage tank.  Ed Wingate uses this for his current magnifier
driver.  Except for the terrible wood and paper based products, I really
believe the coil form material choice is another coiling non-issue.  Just
keep the form material as thin as possible and make sure it is a modern
plastic product!  All the losses in any form are purely dielectric losses.
Choose it as you would choose a capacitor dielectric to operate in the
50-500khz range with low losses.

Richard Hull, TCBOR