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DK3UZ > TECHNI 07.09.05 00:15l 41 Lines 1620 Bytes #999 (0) @ WW
BID : E941D1FDK3UZ
Read: DJ4KI DK1NX GUEST DG4NAU DL1LCA OE7FMI
Subj: Re: Why vacuum tubes?
Path: DB0FHN<DB0RGB<DB0SL<DB0FSG<DK0MNL<DF0HMB<DB0AGM<DB0HHT
Sent: 050906/2204Z @:DB0HHT.#HH.DEU.EU [TCP/IP,JO43XP] BBSX-2.14L $:E941D1FDK3U
In <65466-GB7FCR@bbs.net> g0tez@gb7fcr writes:
> [...]
> 19th century scientists knew about inert gasses so, surely it would have
> made more sense to just fill a bulb with, say, nitrogen which could push
> out the oxygen.
Early thermionic valves (audions) were gas filled. "The Saga of the
Vacuum Tube" has the full history. Hint to help with your question:
Vacuum has no ions.
> Even simpler, would be to connect your bulb containing
> it's filament to another airproof container and set fire to something in
> it, even paper burning at 451 deg F would remove the oxygen from both
> containers, then you melt the glass tube at the top of the bulb and,
> presto! no oxygen, filament won't burn.
And what do you do with the fire's by-products (smoke & ash) which
would settle down all over the place?
> [...]
> Better than paper would have been magnesium which was used in valves to
> remove the last of the oxygen when the pump had sone it's work, a process
> called 'gettering' if I remember clearly.
Getter pills are also made from Barium. The use of presence is deli-
berate: Thermionic valves are still being made (and used), and not just
for display purposes.
> There is a bit of a twist here. If the electric light had been invented as
> a bulb full of inert gas at normal pressure then vacuum tubes, valves,
> would not have come into being as gas stops electrons.
Which is why gaseous and mercury vapour rectifiers just won't work?
> [...]
73, Eddi ._._.
--
dk3uz@db0hht.ampr.org - dk3uz AT darc DOT de - DK3UZ@DB0HHT.#HH.GER.EU
QTH Hamburg-Bramfeld, FN31a
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