Re: twin coil transmission lines (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Thu, 31 May 2007 03:37:33 +0000
From: Sparktron01@xxxxxxxxxxx
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: twin coil transmission lines (fwd)

DC et al

I built an equivalent stripline transmission line using
10 mil Cu strapping 3" wide and Kapton(R) 10 mil
insulation.  Using equations for classic parallel strip line
(graciously provided by Bert Hickman [  HI!!!  ] }
and confirming measurements with a HP
precision LCR meter were within 10% of calculated.
This was a dedicated fixture for an ATE  (Automatic Test
Equipment) application, involving PWM pulse train
power application to a resistive load; so surge
impedance and parasitic reactance(s) had to be
minimized to prevent skewing of test data.

Surge Z was <<5 ohm for a 6' one way path,
(12'  total electrical path).  Only way to make a very low
impedance buswork (why PCB's work well with ground
planes), and used extensively in pulse power work.  
No measurable degradation in performance of EUT
from stripline power fixture.  To put this into perspective,
the best shielded cable commercially available that
could handle load currents (10-12 amps) had 
an apparent Zo (sqrt (L/ft divided by C/ft) of 
35-40 ohms.

A stripline would be a preferable design for interconnection
of Tesla coil components for a large machine, insulation
integrity at HV and RF currents would be problematic.
Polyethylene, either LD or UHMW virgin grades, might be
a better choice then acrylic.   PE also has advantage
of being one of the lowest cost  petrochemical plastics.
The thicker the dielectric (for HV standoff) would require
much wider stripline to maintain similar impedance
characteristics.

FWIW.

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA

 -------------- Original message ----------------------
From: "Tesla list" <tesla@xxxxxxxxxx>
> Original poster: List moderator <mod1@xxxxxxxxxx>
> 
> 
> 
> ---------- Forwarded message ----------
> Date: Wed, 30 May 2007 16:18:56 -0500
> From: resonance <resonance@xxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: twin coil transmission lines (fwd)
> 
> 
> 
> 
> Use 4 inch wide copper strap and sandwhich 1/4 inch acrylic plate between 
> them with a 4 inch wide margin on both sides of the dielectric plate.  I've 
> run up to 60 feet with almost no losses with this type of home-made 
> transmission line.  Inductance is very low.
> 
> Dr. Resonance
> ----- Original Message ----- 
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Wednesday, May 30, 2007 11:35 AM
> Subject: twin coil transmission lines (fwd)
> 
> 
> > Original poster: List moderator <mod1@xxxxxxxxxx>
> >
> >
> >
> > ---------- Forwarded message ----------
> > Date: Wed, 30 May 2007 14:54:42 +0000
> > From: David Rieben <drieben@xxxxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Cc: drieben@xxxxxxxxxxx
> > Subject: twin coil transmission lines
> >
> > Hi all,
> >
> > I have a question regarding the transmission lines between large
> > twin coil systems that's been bugging me for a while now. I have
> > never seriously considered building a large twin coil or magnifier
> > system, mainly due to the large space that one of these systems
> > eats up when assembled. However, I know that there's also
> > considerable line losses in the transmission lines that carry the RF
> > currents from the SG and capacitor to the primary coil(s) and that's
> > the reason that we usually try to keep the tank circuit wiring
> > between the SG/capacitor to the primary coil as short as possible
> > in a basic 2-coil SG system. My question is how do you manage
> > these losses to acceptable levels in the primary transmission lines
> > of large twin coil systems where the 2 primary coils may be
> > spaced 10 to 20 ft. or more apart and wired in series? I would
> > assume that keeping the lines as straight as possible and with a
> > relatively large radius of curvature (ROC) would help to keep
> > the inductive and corona losses, respectively, at bay.
> >
> > Thanks,
> > David Rieben
> >
> >
> > 
> 
> 
> 
>