Re: Safe parameters for stupid human Tesla coil stunts

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Sue Gaeta <sgsparky@xxxxxxxxxxx>

This is true, RF is tricky stuff.

When pipeing RF, even with high frequecy rated conductors, everything in 
the transmission of RF through conductors must be impedance matched, right 
on up to the last component (antenna or whatever) otherwise all bets are 
off and insulation will break down anyway!

If impedance matching of transmission lines is not possible, or feasable, 
such as from a spark gap to the primary tank circuit, or a plate cap to a 
DC blocking capacitor for example, then your only option is to keep wires 
as short as possible, and keep them away from everything. The use of 
standoffs become mandatory, and insulation on wires become meaningless. Any 
time an insulated wire is carrying high frequency (above 40Khz) through it, 
you should make believe that the wire is not insulated at all! Most of the 
old hands on here have experienced this, but since alot of newbies join on 
here all the time, it's good to rehash this stuff.

During my early experimentation with a 50Khz high voltage oscillator, I 
actually burned through a 1" thick slab of H.V. silicone potting. I was 
powering it with 12 volts, and was drawing about 6amps. That's 72 watts 
input. The output RF power was less than half that. If you look at the 
output stage of high powered transmitters everything is on standoffs, and 
in open air.

By the way it's amazing how much I learned about successful tesla coil 
building through being a ham radio operator, and how much I learned about 
RF principals through tesla coiling. Tesla coils make all those subtle 
properties of RF physics become blatently obvious. Instead of making us 
learn Morse Code to pass the exams, they should make you build a VTTC to 
pass an Extra Class exam(although I don't think they even have "Extra" 
anymore). I would become a V.E. again if they did that! :-).

I love RF. It is so much like Voodoo to people who only know DC and low 
frequency AC theory. Did you ever see a streamer run right past an intended 
ground target and hit something else further away that wasn't even 
grounded. The reason is likely to be that the ungrounded object was 
capacitively coupled to ground, and presented a lower impedance path to 
that frequency than the ground rod connected to run of wire on the floor 
attaching to a cold water pipe somewhere, which looked more like an 
inductor. It's something that walking human capacitors should ponder about 
as they confidenly hold that grounded Jesus stick, while approaching the 
sparking toroid :-).

Happy New Year!

Sue

Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: "Black Moon"

Yes, let this be a lession to allways make sure your HV wire is high
freqency rateing if your going to use it as such,