RE: Impedance

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: d a <btoc3000@xxxxxxxxxxxx>


I read this from: 
<http://users.tkk.fi/~jwagner/tesla/tc-plans.htm>http://users.tkk.fi/~jwagner/tesla/tc-plans.htm 
and I have some queries...

The Tesla coil secondary RF ground must be an own ground separate 
from mains ground. Reasons:

1) this separate ground will sink RF current and voltage, which - if 
you used mains ground - would fry all equipment in your house, even 
the surge protectors.

2) also, the mains ground wire is way too thin, and would have a 
considerable impedance at the high frequencies present. High 
impedance is not nice, as the TC base wouldn't be properly grounded 
then, and the wire would have a voltage drop from some 10s of kV on 
the base to 0V somewhere along the wire - i.e. the thin wire could 
still have a few kV some meters away from the coil base (corona, 
electrocution, damaged equipment etc).

3) the other thing that is bad about a high impedance ground is that 
the zero voltage node will shift down along the wire to the place 
where the solid ground is. This will cause a phase shift also in the 
TC secondary, meaning you could get breakouts from any part along the 
coil, not just the top.

for 1) Am I right to say that RF current and voltage is different 
from the HV current and voltage that we are getting at the secondary topload?

for 2) Why would thin wire have a considerable impedance at the high 
frequencies? Is there a formula for this?

for 3) In layman terms, does it mean that having a poor ground will 
cause the zero voltage node to "shift" to the solid ground. What is 
the "solid ground" here?

Thank you so much in advance

Sam