Re: toob coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 3/18/02 6:47:37 PM Eastern Standard Time, tesla-at-pupman-dot-com
writes:


>
> . It has two 500 watt triodes in parallel.  



James,

what kind of 500 watt triodes are you using?  Your efficiency is
pretty good overall. 

Secondary is 6

>
> in. PVC wound with 26 in. of #27 and covered with West Marine System Epoxy
> glass. Pulls 23 amps. Max spark is 18-20 in. I suppose that the turns ratio
> was
> too low with 60 turns primary. There is a fine line here. Too few turns and
> the
> impedance of the primary is too low. Too many primary turns and the turns
> ratio
> is too low. 



>
>    The Tickler coil is easy. Too few turns and the tubes run hot. Too many
> and
> the "grid leak resistor" runs very hot. The tickler coil has to put enough
> voltage on the grid to put the tube into "cut-off". 



The tickler coil provides sufficient voltage swing to the grid.  The grid
leak network (C and R), creates the negative bias that keeps the
tube biased into the cut-off region. 

This is easy to see with a

>
> scope on the tube's grid. Also, you can get an idea from the tube's chart.
>       I like playing with the toob coil. The drawback is that you are charged
> with RF. Everything you touch burns you. I end up with lots of little black
> spots all over my fingers. 



I never touch any metal when I'm running a tube coil.

Cheers,
John


The uwave PS is quite dangerous. The 4000 volts at

>
> lots of current requires caution. I use absolute caution before touching the
> beast. Generally the "one-handed-rule" applies. Keep one hand in your pocket
> when it's live. 
>                                                                            
>                             Later,
>                                                                            
>                                 James
>
>