Beware 
It sounds like an Electric chair you are
Building ------one zap and u are gone!!!
G3kev

Sent from my iPhone

On 14 Nov 2015, at 20:00, Chris Wilson <[email protected]> wrote:

> Hello Andy,
> 
> Saturday, November 14, 2015
> 
> 
> OK, but what about wire breakdown voltages? In all the big air cored
> LF tanks I have seen the windings are well spaced on ceramic, or
> Paxolin type grooved formers, how do I know a close wound toroidal
> coil won't break down?
> 
> 
> I have built a few HV supplies using decent industrial quality iron
> cored transformers, the biggest is 5kV at 1.5 Amps, which can also be
> fed from a 40 Amp Variac, to drop the primary down. I use that in my
> workshop for running a glue drying machine.
> 
> I was also gifted some NOS ceramic triodes, some US, some Russian, and
> would consider having a bash at a valved LF amp, just "because" :) I
> have to say my limited experience of ceramic triodes has shown no
> unreliability, in fact a zero failure rate so long as they are
> gettered before use, if they have lain dormant for years.
> 
> I do have a reasonable collection of failed FET's though :) In
> fairness user error was the demise of most of them.
> 
> 
> Thanks Andy.
> 
> 
>> I'll say it againV = 4.44.F.N.A.B  (all SI units)
> 
> 
>> THAT is how you size ferrite cores.  It tells you more or less
>> everything you need to know to make ferrite transformers.  Keep B to
>> less than 0.1 at these frequencies
> 
> 
>> But.. why would you want to use valves?
>> Expensive, unreliable, high voltages...
> 
> 
>> 'jnt
> 
> 
> 
> 
> 
> 
> 
> 
> -- 
> Best regards,
> Chris  2E0ILY                          mailto:[email protected]
> 
>