[Amps] figuring tube output impedance

[Will Matney]

Chuck,

I have a link below to a Hams website who uses the factor 1.87 instead of 1.8 which he came up with from experimentation. He said it actually gets you closer to the correct values than using 1.8. I think the factor of 1.8 came from the RCA Radiotron book, and everyone generally used it. I have found myself that a lot of factors have been rounded off and will only get you in the ballpark myself. Experimenting by building a lot of amps is a better way to know what they should be. This ham goes through all the steps of doing it and I recommend anyone to read this if they wish to learn how to design an amp. Select any amp he's built as all show the calculations if I remember.

http://www.xs4all.nl/~pa0fri/Lineairs/Lineairs.htm

Best,

Will

*********** REPLY SEPARATOR  ***********

On 2/27/06 at 1:36 PM Partain, Chuck wrote:

>I see a lot of  formulae(is that plural???) on determining the output
>impedance of a tube.
>some say just plain plate volts divided by plate current, some have a 1.8
>x formula  and so on. I Want to determine
>this gu-84b impedance so I can start work on the tank setup. I run 3.9kv
>and I'm GUESSING 2 amp.
> I stuck a 2k in there and played some with the values so far and things
>look ok, no suprises. this is
> my motive for the question. lets hear some opinions! thanks as always.
>
>
>
>
>
>Chuck Partain
>http://home.comcast.net/~KA1MWP
>
>
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