Re: [TCML] 6" Tesla coil plexiglass secondary - FOR SALE

[dfroula@xxxxxxxxxxxxx]

David,

At the time I got into TC work, there were enough cautionary notes about PVC secondaries that I just decided to bypass the issue and go with the plexiglass. The plexi secondaries have always worked quite well for me, not to say others have not gotten perfectly acceptable operation from PVC.

The one 6" PVC TC secondary I made was a nightmare to wind. I mounted it on a lathe, but could never get it centered correctly, as the PVC tube was so irregular in shape. The plexiglass extruded tubes I bought from Midland Plastics were much more dimensionally consistent and easily centered for winding.

Electrically, I have built VLF receiving loops by winding wire on untreated pine, even on mounted doors with nails on each corner. They worked fine, although receiving antennas are quite another thing from a high-power Tesla coil.

I was never able to find much quantitative documentary evidence on the benefits of one over the other. I just played it safe. In the end, it seemed to end up being a "religious" issue.

It does look nice, though! I recall one coiler who wanted to fill his plexiglass secondary with neon. I wonder how that worked out!!! ;-)

Best,

Don

--- On Wed, 1/16/13, drieben <drieben@xxxxxxx> wrote:

> From: drieben <drieben@xxxxxxx>
> Subject: Re: [TCML] 6" Tesla coil plexiglass secondary - FOR SALE
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Wednesday, January 16, 2013, 9:57 AM
> Hi Don and Jon,
> 
> I'm thinking the "truth" here may lie somewhere in
> between your two opposing viewpoints ;^) Don,
> although your position is most likely correct in re-
> gards to the relatively high radio frequnecies (10's
> or 100's of MHz, or more), I believe Jon's position
> is probably more relavent for the relatively very low
> frequencies of TC operation -10's or low 100's
> of KHz (that's 3 orders of magnitude lower!) and
> you would be hardpressed to actually
> notice a difference in the output of a PVC vs. a
> plexiglas formed secondary coil without some pret-
> ty fancy instrumentation. My Green Monster 10 kVA
> pole pig driven, ARSG coil has a 12" gray PVC duct
> pipe secondary form and it really rocks and I've
> never been able to detect notable warmth of the
> form above ambient temperature after running it.
> Of course, with the massive 12x56 topload, I'm
> running around the high 50's KHz, which is ex-
> tremely LOW frequency compared to the typical
> modern radio or television communication frequen-
> cies, with a possible exception of AM bands - from
> the mid 500 KHz to 1.6 MHz range. I'm thinking
> that the SG losses as well as the internal dielectric
> losses of the primary capacitor are far more con-
> sequential, as this is the main place that one tends
> to noticed heat significantly above ambient tempe-
> ratures. And if you have a good, low loss dielectric
> capacitor, you won't notice significant heating here,
> either.
> 
> BTW, "I" have experienced the electret effect with
> PVC formed secondaries and I believe others in
> this forum have mentioned it in the past as well.
> 
> David
> 
> ----- Original Message ----- From: <dfroula@xxxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Wednesday, January 16, 2013 8:35 AM
> Subject: Re: [TCML] 6" Tesla coil plexiglass secondary - FOR
> SALE
> 
> 
> > One interesting effect of using a plexiglass form for
> the secondary is that the plexiglass seems hold a charge
> after the coil is shut off (depending where in the charging
> cycle the coil is shut off). The prevalent theory is that
> the plexiglass exhibits an "electret" effect where the
> polymer structure of the material will hold an electrical
> charge for some time. PVC forms I have used do not seem to
> exhibit the effect.
> > 
> > A true electret is a sort of "permanent magnet", except
> that the material retains a permanent electrical, rather
> than magnetic charge. True electret polymers are used to
> construct electret microphones, tha depend on the charge to
> produce an output signal.
> > 
> > I have gotten minor zaps from a plexiglass secondary
> hours after the coil has been turned off.
> > 
> > Don
> > 
> > --- On Tue, 1/15/13, Jon Danniken <danniken@xxxxx>
> wrote:
> > 
> >> From: Jon Danniken <danniken@xxxxx>
> >> Subject: Re: [TCML] 6" Tesla coil plexiglass
> secondary - FOR SALE
> >> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> >> Date: Tuesday, January 15, 2013, 8:42 PM
> >> On 01/15/2013 11:53 AM, dfroula@xxxxxxxxxxxxx
> >> wrote:
> >> >
> >> > Wound on low-loss plexiglass form. Far
> superior to
> >> lossy PVC coil form!
> >> 
> >> I don't think the difference in RF losses between
> a
> >> "low-loss plexiglass form" and a PVC form are even
> >> noticeable in a tesla coil.
> >> 
> >> Is this just advertising hype, or do have actual
> data from
> >> real-world operation showing "far superior"
> performance with
> >> a "low-loss plexiglass" form?
> >> 
> >> Also, is this a special "low-loss" version of
> plexiglass,
> >> because I have yet to come across any type of
> plexiglass
> >> that specifies lower RF losses in any of the
> plastics
> >> dealers I have come across.
> >> 
> >> Thanks,
> >> 
> >> Jon
> >> 
> >> _______________________________________________
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> >> Tesla@xxxxxxxxxx
> >> http://www.pupman.com/mailman/listinfo/tesla
> >> 
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla 
> 
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