[Amps] figuring tube output impedance

[Conrad_G0RUZ]

Hi Chuck wow that's a lot different from the datasheets that I have seen. Of
course my experience is at VHF with the GU78B. I wonder what the 'true' data
is? I have always believed the data on the ND2X site to be correct but of
course no one is using more GU84B's than Emtron.

Whatever you do please let us know how you go on.

73

Conrad G0RUZ 

> -----Original Message-----
> From: Partain, Chuck [mailto:Chuck_Partain at maxtor.com] 
> Sent: 27 February 2006 19:02
> To: conrad at g0ruz.com; amps at contesting.com
> Subject: RE: [Amps] figuring tube output impedance
> 
> I COULD easily enuf screw a smaller transformer into this project...
> but i'm not convinced yet!! I have seen 5.5 max peak can hit 
> this tube but will go along here for a while and see. 
> 
> My first research and questions around the tube led me to  
> believe that 4kv was a good amount and I have gone with that, 
> although over the past 6 months or so I have been rethinking it. 
> 
> this PDF from the emtron website I think. It says 3.3kv with 
> 5 or so instantaneous.
> 
> 
> 
> 
> 
> -----Original Message-----
> From: amps-bounces at contesting.com 
> [mailto:amps-bounces at contesting.com]On
> Behalf Of Conrad_G0RUZ
> Sent: Monday, February 27, 2006 1:48 PM
> To: amps at contesting.com
> Subject: Re: [Amps] figuring tube output impedance
> 
> 
> 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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> 
> 
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