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## [Fwd: Re: [Amps] Re: GU-84b: Drive power required for full poweroutput ?

 To: amps@contesting.com [Fwd: Re: [Amps] Re: GU-84b: Drive power required for full poweroutput ?] frank_goenninger@t-online.de (Frank Goenninger) frank_goenninger@t-online.de Sun, 28 Mar 2004 11:09:40 +0200
 ```Hi again - sorry to bother you again... Taking all the inputs so far for my GU-84b grid driven amp I come to the following parameterization: Ua = 2750V Ia = 1.5A @ Ug1 = -65V Ug2 = 395V Expected Pout = 2750V * 1.5A * 58% = 2.3 kW Assumption: 56% efficiency of tube, class AB1 Parameters for Pout,max = 750W , the "German Thing"(tm): Ua = 1825V Ia = 0.75A @ Ug1 = -75V Ug2 = 395V Cut-Off Bias is -150V for Ug1 for both cases. Correct so far? Mni tnx for feedback! vy 73, Frank DG1SBG On Sat, 2004-03-27 at 01:48, R.Measures wrote: > >Hi Peter, Rich, & all the others on this list, > > > >thx for replies. Having expose myself as mostly new to tubes and such, I > >see that the GU-84b allows for -150V on the grid. > > > >Given a 50 Ohm input circuit about 100V peak will be produced by 100W > >drive power. > > > >This would require to bias the grid at about -100V which is within > >limits of tube parameters. > > > >What would be the consequences out of this? Rich, you mentioned a > >typical value of about -80V for the grid bias. > > â -80v looks like the needed bias potential required to produce a > reasonable ZSAC. Thus, +80v of peak drive would be needed to produce a > peak 0v on the grid. > > >Sorry, I still do not > >have any suitable datasheet (and found none on WWW too)... > > > >So my parameters for the GU-84b are: > > > >Ua = 3000V (Anode) > >Ug1 = -100V (Grid) > > â -100v on the grid does not produce enough ZSAC. > > >Ug2 = 375V (Screen) > > > >What would be the resulting values for > > > >Ia > >Ig2 > > > >??? > > > >Thx for all the assistance so far! > > > ur welcome, Frank > > > > > > > > > > > > > >On Fri, 2004-03-26 at 17:06, R.Measures wrote: > >> >In einer eMail vom Do, 25. MËÂrz 2004 18:21 MEZ schreibt > >> >frank_goenninger@t-online.de (Frank Goenninger): > >> > > >> >>I initially intended to ask if about 1A of input current will be enough > >> >>to really get reasonable power output? > >> >> > >> >>This comes from a simple calc from Pout of the TRX, which is about 100W > >> >>producing about 1.4 A of current into 50 Ohms. > >> >> > >> >>Also, for this tube, what type of input circuit would you recommend when > >> >>trying to cover all bands up to 30MHz ? > >> > > >> >Hi Frank, > >> > > >> >Since this is a tetrode it will be run without grid current, > >> >the driver does not need to deliver current, just voltage. > >> >Typically the grid is loaded with a 50 Ohm dummyload, into > >> >which drive voltage developes without tuned circuits. > >> >For the higher bands you probably have to compensate the high > >> >input capacity with a small coil in parallel. > >> >I guess you will need not more then 25W drive for full throttle. > >> > > >> âÃÂ My guess is that with a 50-ohm termination, somewhat more than > >> 25w > >> will be needed to drive the grid up to the 0v point. The grid potential > >> is typically -80vdc. 64w is needed to produce 80v-pk across 50-ohms. > >> > >> cheers, Peter > >> > >> > > > > > _______________________________________________ > Amps mailing list > Amps@contesting.com > http://lists.contesting.com/mailman/listinfo/amps > > _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps ```
 Current Thread [Fwd: Re: [Amps] Re: GU-84b: Drive power required for full poweroutput ?], Frank Goenninger <=