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Re: more tube coil mayhem :)



Original poster: "Area31 Research Facility by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rwstephens-at-hurontario-dot-net>

Shad,
 
Try removing 3 of the four 833A's and do powered tests.  Then using just the
one triode, try it in all four sockets, testing one position at a time.  If
your parasitics disappear then you can try adding a second 833A and go through
the procedure again.  This may give you some clues.
 
Are you running 100 ohm 2 watt carbon comp resistors in series with each tube's
control grid ?  Are you running 47-51 ohm 2 watt carbon comp with a few turns
of #20 magnet wire tightly wound around them and in parallel as 'birdie
suppressors' in series with each plate connection before the point they are all
summed?
 
Before you can excite a secondary resonator to make HV fuzz, you need a stable
RF power oscillator.  Remove that secondary coil for now and replace it with
two turns of #8 or #10 AWG insulated copper wire wound directly next to the
plate winding on the tank coil.  Run the leads of this temporary pickup coil to
a bank of 120 volt 0r 230 volt incandescent light bulbs.  I have a large
plywood panel wired with 1000 watt, 230 volt lamps for this purpose in the
lab.  You can add or remove load by partially screwing and unscrewing
individual lamps in the large porcelain mogul sockets.
 
Rob Stephens
>
> ----- Original Message ----- 
> From: <mailto:tesla-at-pupman-dot-com>Tesla list 
> To: <mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com 
> Sent: Tuesday, January 29, 2002 21:18 
> Subject: more tube coil mayhem :)
>
> Original poster: "Sundog by way of Terry Fritz
> <<mailto:twftesla-at-qwest-dot-net>twftesla-at-qwest-dot-net>"
> <<mailto:sundog-at-timeship-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
>
>
>
>
>