Richie's Homepage and other topics

• To: tesla-at-pupman-dot-com
• Subject: Richie's Homepage and other topics
• From: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Thu, 09 Dec 1999 20:27:35 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi all,
          I just visited Richie Burnett's homepage and would like to 
congratulate him on an excellent piece of work. For a well laid out 
and definitive description of spark gap TC operation it is a doozy.
      I then visited Alan Sharp's site through the UK Teslathon links 
and had a look at the solid state coil descriptions. I have the odd 
comment to make:

(1)     Mark Barton's 10kW flamethrower was definitely using IRF840 
FETs. 
(2)     Duane Bylund's use of DC resistance as a starting point for
matching a driver to a secondary could IMHO be bettered somewhat
but there is still a rider.  Firstly, a better match for the driver to a non-
sparking coil could be done by *accurately* measuring the Q of the 
coil and deriving its ESR using  R = SQRT(L/C)/Q.  This figure is 
considerably higher than the DC resistance of the coil in general 
and should be good for direct coupling. For k < 1 this figure would 
be higher.
The rider: this figure would also be better for sparking conditions
(corona in particular) as the impedance at the base of the 
secondary rises while the load impedance at the top reduces ( I 
have measured this and infer that 1/4 wave transformer principles 
do apply to the secondary - the base impedance swings about Zo^2
in accordance with loading).  This is my opinion anyway. I 
measured this using link coupling to the base of a resonator a few 
years ago.  Comments, measured refutations welcomed.

Regards,
Malcolm

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