Thanks for the information on the getters in 3-500Z and 8877, Tom. It
is refreshing to hear factual info about some very common amateur
power tubes. The man at Econco is very knowledgeble for some of the
glass tubes that were planar triodes made by the former Eimac Salt
Lake City operation. He would also give you the correct answer if he
knew it. I believe that it is a moot point now.
W8JI said:
>Rather than take second-hand info, you can find books on the
>subject. There are entire chapters on gettering.
>
>Try the Electronic Designers Handbook and other detailed
>engineering books. Eimac mailed me 19 pages of information in
>1982 titled "Getters and Their Function in Vacuum Tube
>Manufacture".
The various editions of Walter Kohl's textbooks, Materials and
Techniques for Electron Tubes (mine is 1960, GTE) also cover the
various methods of Gettering vacuum devices.
As for getters in cold tubes, we have tubes from RCA which had a
glass amphule inside, which was broken open during the final pinchoff
process of the tube. I have one sitting in my office in front of me.
The have various compounds in them, which flash getter during that
moment. I have no idea if they are useful over the life of the tube
or only during that step. I do know that the getters in 4CW250,000B
tetrodes are near the filament bottom and become more absorptive when
the tube is lit up.
Sorry for the digression on getters here, somehow we seem to get
easily diverted on some innane topic like this and then back to the
same old stories. I'll step back and watch.
John
K5PRO
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