[Amps] Tetrodes

[ad5gb]

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 at stanford.edu > wrote:
From:  [mailto: gdaught6 at stanford.edu]
To: g3sek at ifwtech.co.uk, amps at 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>> 
_______________________________________________ Amps mailing list<br>> Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps<br><br>George T. Daughters, K6GT<br><br><br><br>_______________________________________________<br>Amps mailing list<br>Amps at contesting.com<br>http://lists.contesting.com/mailman/listinfo/amps<br>

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