Re: [TCML] valve coil problems

[<lightningfor@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Carl,
Thanks, I will try it out.

I am definately interested to try the driver idea you mentioned though.
Can you suggest a source of info to take some of the R&D out of it?

If I remember correctly you did a similar valve coil recently...
Do you think it could be scaled up, given that I would need about 500
watts of RF power to drive the grid into Class C.

Thanks, Carlos

On Tue, 01 Nov 2011 12:58:37 -0700, Carl Noggle <cn@xxxxx> wrote:
> Hi, Carlos,
> 
> If you have a scope, you could shock-excite the secondary and measure 
> its resonant frequency.  Take it away form the primary, then put a 
> one-turn coil around the bottom (bottom of the secondary is grounded) 
> and hook the one-turn coil up to the scope.  then flick a 9V battery 
> across the leads to the one-turn coil.  With persistence you should be 
> able to get a damped oscillation and measure the frequency.
> 
> As a fix, try resonating both the primary and the grid coil at the 
> operating frequency.  Or you could make a series-resonant circuit to put

> across the grid coil--the L should be 2 or 3 times that of the grid 
> coil, with capacitor to resonate at the third harmonic
> 
> Or for that matter, you could try running it at the higher frequency.
> 
> I still suggest driving the grid with a low-impedance square wave.  Then

> you can run in class C.  Also, make sure that your screen grid supply is

> well-bypassed.
> 
> Good luck--sounds like a cool coil.
> 
> ---Carl
> 
> 

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