Re: more tube coil mayhem :)

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

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

The secondary is a parallel tuned circuit with a high Q. The change at the
tuning point is sharp and the voltage jumps high and that is easy to see
with a scope.The primary is not so easy, it is low Q series circuit that
dips at resonance.  put your signal gen across the spark gap, and the scope
across a series resistor. When you hit resonance the resistor voltage will
increace as current increases in your signal gen. Shift the frequency back
and forth to find the peak. The lower power your sig gen is the harder it
will be to see. Another way is to use a coil antenna on your scope to see
the peak at resonance. 10 turns or so next to the primary to the vert input.
   ROBERT  H    P.S. Power OFF !!!!!

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Tue, 29 Jan 2002 19:18:24 -0700
> To: tesla-at-pupman-dot-com
> Subject: more tube coil mayhem :)
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Wed, 30 Jan 2002 06:44:05 -0700
> 
> Original poster: "Sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <sundog-at-timeship-dot-net>
> 
> Hiya all!
> this quad 833 coil is a real project/PIA/hpadache/adventure.
> 
> The problems I have to deal with at this moment
> low plate voltage.  I'm going to use a doubler first off on both MOT's,
> later on I'll try 2 mots in series on each 240v leg.  time to go MWO
> scroungeing. 
> Filament tranny - the secondary gets burning hot, too hot. THHN melts it's
> insulation and *BOOM!*  Got to wind a suitable filament tranny.  40A cont
duty
> is a lot of current.
> Nasty 1.8mhz and 735khz parasitic oscillations.  The 1.8mhz were damped a
> lot by adding a ferrite core choke to the plates.  The 735khz oscillation
is a
> mystery.  I can't pin it down, so I don't know where to try eliminatinig
from.
> There's of course a strong 60hz hum (from the filaments, but that's not
> causing
> my any trouble).  But that 735khz is really tearing stuff up, and it's pretty
> strong (about 1/3 the amplitude of the 423khz main driving frequency).  It
> doesn't make a whole lotta sense.  Could a high Q primary be the cause of
> this?  (somehow fixing network servers doesn't help me with working on tube
> coils....) 
> 
> Also!  How do I use my sig gen and scope to find Fres of an LC circuit? (tank
> circuit).  What do I look for, and how do I hook it up?  Scoping
secondarys is
> easy.  
> 
> 
> 
> ---------------------------------
> Shad (Sundog)
> G-1 #1203
> 
> 
>