Ian, please turn off the bubble machine, or whatever has to happen!
I've gotten about 10 copies of this message. Or is it just me?!
73,
On 12 Jul 2005 at 23:04, Ian White GM3SEK wrote:
> R wrote:
>
> A great deal, but I don't have time to trade the same old one-liners
> with him, yet again.
>
> However, the following are genuine questions so I'll try to answer
> them.
>
> >> This is a deposit of chemically active metal,... ... In larger
> >>transmitting tubes the
> >> getter is usually something like zirconium, which needs a higher
> >> temperature to function correctly.
> >
> >Does zirconium gettering take place at room temperature?
>
> The gettering (adsorption) reaction that traps the gas goes faster at
> higher temperatures. Gettering by zirconium does take place at room
> temperature, but at a very slow rate.
>
> To complete the story, there is also an opposite de-sorption reaction
> that releases the gas. At normal anode operating temperatures,
> adsorption goes much faster than desorption so there is a net
> gettering effect. But at very high temperatures the desorption
> reaction overtakes the adsorption, so there is then a net release of
> gas. That is how the tube structure is de-gassed during manufacture,
> by heating it to a much higher temperature than normal.
>
> >Do 3-500Zs utilize a zirconium getter?
>
> As far as I'm aware, 3-500Zs do have a zirconium getter on the plate,
> so it works well when the plate is hot. In answer to Vic's question,
> that does seem to imply that those tubes need to be run with some
> plate dissipation if there is a need to clean up the vacuum... but I'd
> defer to anyone with more practical experience.
>
>
> --
> 73 from Ian G/GM3SEK 'In Practice' columnist for RadCom (RSGB)
> http://www.ifwtech.co.uk/g3sek
> _______________________________________________ Amps mailing list
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George T. Daughters, K6GT
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