[Amps] figuring tube output impedance

[Conrad_G0RUZ]

I would NOT run 3.9 kV on a GU84b, that is way too high, I have used the
GU78B and I wouldn't run that much HT on a GU78B and it is a considerably
better tube.

Look at this http://www.nd2x.net/gu84b.html . I would go for an RL of around
650-700 ohms for a GU84B with 2.2kV @ 2 amps. I know that the VHF guys have
had bad experiences running this tube with high HTs, they go bang quite
easily. Of course they will run to 2.75 to 3kW output without exceeding
ratings too much.

73

Conrad G0RUZ 

> -----Original Message-----
> From: amps-bounces at contesting.com 
> [mailto:amps-bounces at contesting.com] On Behalf Of Partain, Chuck
> Sent: 27 February 2006 18:36
> To: amps at contesting.com
> Subject: [Amps] figuring tube output impedance
> 
> 
> 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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