* Carbons Sent to: Kukkonen-at-snakemail.hut.fi

 Quoting: Kristian Ukkonen 

 KU> A just heard a nice idea for a ground to be used when one    
 KU> transports a Tesla coil to some other place than the "lab"   
 KU> for demonstrations: One could connect some copper-plate to   
 KU> the end of a ground-strap and sink this to the nearest       
 KU> sewer!!! 

This is an excellent idea, and one I have advocated for years.

 KU> This could be a possible solution (temporary) for getting    
 KU> fairly good (compared to water-pipe) ground as the           
 KU> sewer-system does not use metallic pipes... What do you      
 KU> think?

In this part of the world many basement sewer connections in
older houses are made with large diameter cast iron pipes, which
is a ready made RF ground. The surface of the cast iron needs a
good scraping or light grinding to remove the rust retardant
coating. I dress the prepared surface with electrical corrosion
retardant. Several turns of ground strap is then wrapped around
the iron pipe and the connection is clamped down with a large
stainless steel strap clamp. This is better than temporary.

A second method I have used with sucess with plastic drain pipe
systems in newer homes. I locate the lowest drain access in the
basement and fish about 10 feet of two inch wide aluminum strap
into the drain towards the street. It is important to determine
that the fished in strap is in a drain that always has standing
water in it, and I try to fish the strap towards the street

RF grounding systems that incorporate sewer systems are very high
Q providing sufficient contact with water is obtained. Nobody
else grounds to sewer systems so you don't have to worry about RF
leakage into somebody else's ground (telephone, cable TV, 60
cycle, etc..). The sewage water has pretty good RF conductivity
due to the presence of detergent salts and ammonia from waste
breakdown. I know a guy who fires up to 8 kVA using the basement
sewer for his RF ground and he has been very pleased with the
system performance. 

 KU> ps. I got my primary and secondary ready - and almost got    
 KU> the materials for the caps so I'll be ready to fire soon..   
 KU> and could use the sewer as the ground (soil) is very frozen 

Give us some specs on your project to date.

 KU> btw: Richard : what do you think about using multiple sheets 
 KU> of .5 mm thick polypropene together to get the required      
 KU> _length_ for the di-electric sheet - with or without welding 
 KU> the pp-sheets together? Unfortunately the sheets are only    
 KU> 1.2 meters long.. I just though about it and basicly it      
 KU> wouldn't matter whether even if there was a little gap       
 KU> between pp-sheets as it would be filled with oil.. (the gap
 KU> is not between turns but between sheets - 3 sheets to get 3  
 KU> meters, and three layers of these for each plate to get 1.5  
 KU> mm thick) 

I don't know. Sounds complicated (it may not be, it's just an
opinion), and my experience shows the more complicated the cap
construction, the better they fail! 

Simple stacked plate caps are tedious (ask Mark Conway) but they
are not complicated. I would build a flat plate cap before I
would build a rolled cap using sections of dielectric that were
too short for the construction. 

Richard Quick

... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12