Re: Tube Type Tesla Coils

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Tube Type Tesla Coils
From: Tesla List <storey-at-stic-dot-net>
Date: Sat, 15 Mar 1997 09:39:02 -0600
Approved: tesla-at-stic-dot-net
Subject: 
        Re: Tube Type Tesla Coils
  Date: 
        Sat, 15 Mar 1997 10:08:06 -0500 (EST)
  From: 
        richard hull <rhull-at-richmond.infi-dot-net>
    To: 
        Tesla List <tesla-at-pupman-dot-com>


A
>  Richard -
>
>  One of the problems I ran into in trying to measure the VSWR of a
>Tesla
>coil was to decide where to connect the VSWR meter. Hams connect the
>meter
>in the transmission line between the transmitter and antenna. But there
>is
>no transmission line with a Tesla coil. One way to make the test is to
>set
>up a robust oscillator and connect it to the TC secondary coil via a
>calibrated transmission line and a bridge type VSWR meter. This test
>would
>not be static and would be at low voltage. 
>
>  The Corum's said they measured a TC at 1000 VSWR but did not say how
>it
>was done. Dr. Gary Johnson of Kansas State University measured a TC at
>200
>VSWR. He gave some details on this test at the 1992 Tesla Symposium in
>Colorado Springs.
>
> The advantage of knowing the VSWR of the TC is to determine if the TC
>is
>properly tuned for maximum output. The Q factor can also be found with
>this
>test. This Q factor should then be coordinated with the operating spark
>gap
>duration.
>
> Has any coiler researched this parameter? This test is also related to
>the
>Smith Chart but I have not found that very helpful. The Smith Chart was
>designed for radio work.
>
>  John Couture
>
>John,

I am sure the Corums must have measured in the base of the Tesla
resonator,
if they made the measurement with a discharging coil.  Otherwise they
did it
in a static mode where all bets are off.  I have never really worked
from
this angle as I felt the result would yield little of value since I am
after
sparks and they are aesy enough to see and adjust for.  You are exactly
correct in that the smith chart is for CW radio work and regular pulsed
microwave siganls where the load is fixed and invariant.

I fear we have a tiger by the tale in a running tesla coil! 
Insturmentation
has to be considered carefully and the results viewed as transitory at
best.
With a heavy leaning towards interpretation of largely qualitative
results.

Richard Hull, TCBOR