Re: VTTC/ would this work?

["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 9/28/02 4:04:56 PM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:


>
> I found that Alan Jones has a very simple 811A circuit.  Here it is, but 
> look at the values i intend to use rather than what he has:
>
> http://personalpages.bellsouth-dot-net/a/j/ajones18/811Aschematic.jpg
>
> T1- 2000v MOT
> T2- 6.3v 3A filament transformer( i know i need 4A, Fair radio sent me the 
> wrong transformer!! is this a problem, it worked before)



Steve,

That transformer will be fine.

>
> C1- 940pf 20kv doorknob
> C2- 900pf 8kv Poly caps.  (would 6kv be acceptable? i could get more pf 
> then)  



6kV is fine.

I also have a .01uf 10kv cap, but this seems way too big.

yes, too big.

>
> L1- 30 turns of #14 solid 6.25" diameter.  Tapped on turns 10-30.
> L2- 25 turns of #24 magnet wire 6.25" diameter.  No taps (is tuning needed 
> on this coil?)



no tuning, but it controls the amount of grid feedback.  I like to
make this coil so it can be slid closer or farther from the primary,
but if you're copying someone's design, the sliding feature is not needed.


>
> L3- 2 3/8" diamter.  12" wraped with 28awg magnet wire.  Unknown topload
> L4- 10 turns of wire on R2
> R1- either 10kohm 10 watt or 5kohm 20 watt, whats better?
> R2- Is the L4 R2 combo even needed?  If so i guess i'll shoot for about 
> 50ohms



Not really needed.  It stops parasitics, and protects the tubes
from arc-overs.  


>
> David Trimmel uses a very similar circuit with 2 803s.  He does not use the 
> L4 R2 combo. Does the primary sit below the grid coil(opposite the diagram) 



primary can be above or below the grid coil, doesn't matter.  
If the coil doesn't oscillate, reverse the grid coil leads.

>
> Also, if i were to add a second 811A, will the coil be in tune still?  or 
> will i have to change any of the components values(besides re-tuning the 
> primary)?  



The coil will stay in tune.  With two tubes the system will tolerate
a larger tank cap than with one tube.  In that case retuning will
be needed if you change the tank cap value.  But you don't have
to do that.  You may need to adjust the grid leak resistance for
two tubes for best results.

John

     Thanks guys, i know that ive been posting alot and changing my 

>
> mind on just about everything, but this looks promising.
>
> Steve Ward.
>
> _
>