Actually the getter is there all the time and what you are speaking about is
how to reactivate the gettering process.
By heating "some" metallic getters such as coated plates, they attract more
ions and molecules of gas in vacuum device. Running the plate with color
is risky in itself as it may liberate additional molecules from the plate which
then have to be absorbed. Some tubes may be
worsened after this process.
There are good explanations (probably better than WWW or Wiki) in the RCA tube
design book, found on Pete Millet's old books site, and in the books by Kohl on
Vacuum tube materials from the 1960s.
Some large tubes have cold getters as well, which do not rely on heat. They are
typically a chemical coating in a glass ampule that is broken open by a tool or
process during the final stages of pinching off a tube.
Burle tubes often have this type of getter and they do not run the plate cherry
at all, period.
73
John
K5PRO
> Date: Tue, 13 Sep 2011 07:41:41 -0700
> From: Patrick Barthelow <apolloeme@live.com>
> Subject: [Amps] 2 Ways of Gettering...
> To: <amps@contesting.com>
> Message-ID: <SNT115-W363FCE56C2B09C3E0BAB85DF050@phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
>
> Hello Willy,
>
> What I learned from this forum, was a second
> gettering process, after being familiar with the first, and which I have
> used on 3-500Z family of tubes. That is the process of
> running the plate with significant color which activates the gettering
> material on the outside of the plate, to do the gettering process.
>
> The
> gettering of External Anode tubes, is different, where sustained
> normal temperatures of the hot cathode, provide the gettering action,
> which is done by the cathode, not the plate.
> 73,
> Best Regards,
> Pat Barthelow AA6GE
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