Ian has a virus. It's called Microsoft.
(sorry couldn't resist)
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Randall D. DuCharme (Radio AD5GB)
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--- On Wed 07/13, < gdaught6@stanford.edu > wrote:
From: [mailto: gdaught6@stanford.edu]
To: g3sek@ifwtech.co.uk, amps@contesting.com
Date: Tue, 12 Jul 2005 21:16:58 -0700
Subject: Re: [Amps] Tetrodes
Ian, please turn off the bubble machine, or whatever has to happen! <br>I've
gotten about 10 copies of this message. Or is it just
me?!<br><br>73,<br><br><br><br>On 12 Jul 2005 at 23:04, Ian White GM3SEK
wrote:<br><br>> R wrote:<br>> <br>> A great deal, but I don't have time to
trade the same old one-liners<br>> with him, yet again.<br>> <br>> However, the
following are genuine questions so I'll try to answer<br>> them.<br>> <br>> >>
This is a deposit of chemically active metal,... ... In larger <br>>
>>transmitting tubes the<br>> >> getter is usually something like zirconium,
which needs a higher<br>> >> temperature to function correctly.<br>> ><br>>
>Does zirconium gettering take place at room temperature?<br>> <br>> The
gettering (adsorption) reaction that traps the gas goes faster at<br>> higher
temperatures. Gettering by zirconium does take place at room<br>> temperature,
but at a very slow rate.<br>> <br>> To complete the story, there is also an
opposite de-sorption
reaction<br>> that releases the gas. At normal anode operating
temperatures,<br>> adsorption goes much faster than desorption so there is a
net<br>> gettering effect. But at very high temperatures the desorption<br>>
reaction overtakes the adsorption, so there is then a net release of<br>> gas.
That is how the tube structure is de-gassed during manufacture,<br>> by heating
it to a much higher temperature than normal.<br>> <br>> >Do 3-500Zs utilize a
zirconium getter?<br>> <br>> As far as I'm aware, 3-500Zs do have a zirconium
getter on the plate,<br>> so it works well when the plate is hot. In answer to
Vic's question,<br>> that does seem to imply that those tubes need to be run
with some<br>> plate dissipation if there is a need to clean up the vacuum...
but I'd<br>> defer to anyone with more practical experience.<br>> <br>> <br>>
-- <br>> 73 from Ian G/GM3SEK 'In Practice' columnist for RadCom
(RSGB)<br>> http://www.ifwtech.co.uk/g3sek<br>>
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http://lists.contesting.com/mailman/listinfo/amps<br><br>George T. Daughters,
K6GT<br><br><br><br>_______________________________________________<br>Amps
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