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.
> >> >
> >> âàMy 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
|