[Boatanchors] Smart People: Gassy Tubes Reversable?

[J. Forster]

As I've written before, if you run the tube with filament and plate
voltage, biased to 10%-20% of nominal Ip for a couple of days, many tubes
clean up and become gas-free.

-John

====================



> Yes, that all rings with what I remember from physics classes. So tube's
> can get gas from outside the envelope as well as from internal outgassing.
> Which unfortunately still leaves us with the questions of whether there
> are practical cures. The links provided by VE3BBM and W5JO seem to provide
> some material for thought & experiment.
>
>  Wayne
> WB4OGM
>
>
>
> -----Original Message-----
> From: J. Forster <jfor at quikus.com>
> To: hwhall <hwhall at compuserve.com>
> Cc: arc5 <arc5 at ix.netcom.com>; boatanchors
> <boatanchors at mailman.qth.net>; milsurplus
> <milsurplus at mailman.qth.net>
> Sent: Tue, Dec 3, 2013 1:19 pm
> Subject: Re: [Boatanchors] Smart People:  Gassy Tubes Reversable?
>
>
>
>
> Yes,
>
> Gasses diffuse through glass, even if the metal-glass seals are perfect.
>
> It depends on:
>
> Pressure differential
> Glass permeability
> Gas molecule size.
>
> If you have a glass Dewar and you leave it exposed to He overnight, it'll
> be useless the next day. The He will diffuse through the glass and spoil
> the vacuum. HeNe LASERS die for the same reason.
>
> BTW, gasses diffuse through metals too. Hydrogen diffuses through hot
> Palladium very well. That's how untra-pure H2 is made.
>
> This same physics is use to enrich uranium, as in Iran.
>
> -John
>
> ===================
>
>
>
>
> > >
> > The diffusion rate through a semi-permeable membrane detends on the
> > pressure difference across the membrane.
> > >
> >
> > Hi, John. I think you are referring to gas diffusing through the tube
> > envelope? I hadn't considered that. I was assuming gas "leaking" in
> or out
> > via wire lead seals, sort of like through nano-cracks between
> materials.
> >
> > 73,
> > Wayne
> > WB4OGM
> >
> >
>
>
>
>
>
>
>