Re: [TCML] Dual-triode VTTC (811A/812A)?

[Steve Ward <steve.ward@xxxxxxxxx>]

The only thing id worry about (and this is an un-educated worry), is that
because of the gain mismatch, you may end up needing to use different grid
feedback windings (or a tapped winding).  At least in the power-conversion
world, a push pull drive must be *really* well matched, or you risk
saturating the transformer you are driving because of the slight "DC" bias
that having non-symmetry will provide.  Obviously a VTTC is air core, and
cant saturate, but you might still end up with something out of balance,
though im not sure to be honest.  If i had to guess, it would end up
stressing one tube more than the other.

BTW, my 811A coil (and any of my VTTCs) were never push-pull, always just
single ended oscillators.  Push pull is a good way to go if you dont mind
the extra complexities, its sort of like doubling your primary drive
voltage.

Steve

On Tue, May 11, 2010 at 9:26 PM, Christopher Karr <chriskarr4@xxxxxxxxxxx>wrote:

>
> My thoughts, exactly. My question is this: would it certainly work?
>
> - Christopher Karr
>
> > sure that would probably work.
>
> > On 5/9/10, Christopher Karr <chriskarr4@xxxxxxxxxxx> wrote:
> > >
> > > Hello everyone,
> > >
> > > I was curious as to whether or not a pair of vacuum tubes which are not
> > > matched (811A and 812A, in this case) might be usable in a
> push-pull-type
> > > VTTC (such as the dual-811A VTTC on Steve Ward's page). As far as I can
> > > tell, the only major difference between the two is the gain, though the
> > > rated drive-power, drive-voltage and output-power (as well as
> dissipation)
> > > are equivalent.
> > >
> > > If this isn't a possibility (or there's a likelihood of near-immediate
> > > failure), may I ask why?
>
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