From: "B2"
Date: Sun, 10 Sep 2000 17:02:18 -0400
Subject: Re: [TSSP] Mystery of the missing loss
Hi Terry, All,
What is the frequency scale along the bottom axis of your graph? =
Rac is is in Ohms?
Cheers,
Barry
----- Original Message -----=20
From: "Terrell W. Fritz"
To:
Sent: Sunday, September 10, 2000 12:09 AM
Subject: Re: [TSSP] Mystery of the missing loss
> Hi Boris, All,
>=20
> At 03:52 AM 9/8/00 -0700, you wrote:
> snip...>
> >Hi All,
> >Althought,I have been present on TSSP list from its
> >first days,this is first post of mine (very occupied
> >lately,and can't manage to check email on regular
> >basis as I used before:))
> >
> >Few comments regarding measured too low Q :
> >Whenever I see measured Q of unloaded secondary =20
> > in order of 50 I can claim:
> >If Z coil is resonably high ,which in most TC
> >secondaries is,low Q could be the result of following
> >things:
> >1.)Rdc is too high becouse of too thin wire diameter
> >used.
>=20
> Using wire gauge tables, my Rdc should be 68.986 ohms. My coil =
measures
> 69.5968 ohms (OK, I have a nice meter ;-)) I examined the trusty o'l
> secondary and despite a few minor cosmetics it seem in excellent =
shape.
> Certainly no spots that would worry me in the least.
>=20
> > 2.)Something is poorly made in secondary construction
> >such as shorted turn top isotropic capacity effect
> >apperance,nonlinear wounding and eddy currents loss
> >area presence etc.
>=20
> The secondary is in excellent condition. I probed around for a =
shorted
> turn, but a simulation test with an extra shorted wire showed the =
dramatic
> effects such a thing would make. Since the inductance and other basic
> parameters are the same as years ago and the secondary is not normally =
a
> surface arcer or anything like that, I will rule out damage and =
shorts.
>=20
> >3.)Possibly extra high dielectric loss in coil form=20
> > (unlikely here I think)
>=20
> Now this I can NOT rule out! The secondary seemed to have much higher =
loss
> at low frequencies than at high!! Using my vacuum cap (which actually
> showed a loss higher than my super cap!) I could clearly see that =
higher
> frequencies had higher loss. Here is a little chart I made of the
> effective secondary resistance vs. frequency. I made it with the =
vacuum
> cap by varying the capacitance and finding the effective Rac.
>=20
> http://216.160.168.190/TeslaCoils/Misc/PaulNich/BRacvF.gif
>=20
> Basically, it says something is getting very lossy very fast as =
frequency
> increases. I have no idea what, but the larger toroid case was =
probably
> less lossy due to the frequency being lower rather than the fields and =
such.
>=20
> This secondary is a 1/8 inch thick cardboard impregnated with paraffin =
wax
> "sonotube" used for circular concrete forms. This wire may have had =
an
> oxide layer at the surface before it was coated. The vacuum cap is
> probably more lossy at low capacitance than high Maybe the =
polyurethane
> coating is doing something... The list goes on... but I seem to be
> getting super high loss as frequency increases.
>=20
> >4.)EM Coupling of secondary with enviroment and losses
> >outside a coil structure.
>=20
> I have done such tests a number of times in a number of places and =
gotten
> similar results. I don't have an oxygen free silver plated room =
coated
> with a gold anti-oxidation layer or anything, but the room is not all =
that
> unusual... I would guess the previous option three...
>=20
> >
> >I don't belive that Terry made serious mistakes
> >relating 2 and 3.Neither that the reason for very high
> >Garry Johnson's secondary coil Q in order of 500 =20
> >is some kind of superior secondary construction.
> >But I do belive it is due to point 4.
> >That would be the reason:Enviroment and resonator
> >position in it.
> >I'm quite convinced Terry's secondary coil Q results
> >would be much better in different enviroment
> >conditions.
>=20
> I have played with some modelling and I think the "room" is far enough =
away
> that it should not be a factor. It is raining now so outside is not =
an
> option. There are a number of things in the Rac loop but the coil =
form
> really does seem lossy to me...
>=20
> The science goes on...
>=20
> Cheers,
>=20
> Terry
>=20
>=20
> > =20
> >Regards,
> >Boris
> >
> >__________________________________________________
> >Do You Yahoo!?
> >Yahoo! Mail - Free email you can access from anywhere!
> >http://mail.yahoo.com/
>=20
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.