(Fwd) RE: [AMPS] Alpha models: 91B vs. 89

[George T. Daughters]

hi morel and "amps" folks,

morel wrote,

> >>Input           Tuned input not req'd   Tuned Input
> >
> >Tuned input is expensive but is a "must" not only for purists.
> >

i have to disagree with that one!  if an amp (triode *or* tetrode) is 
cathode driven, then morel is 100% correct... but the 91beta is *not* 
cathode driven.  the exciter drives what is essentially a 50-ohm 
dummy load, and the amps grids look at the voltage across this load.  
"tuned input not req'd" is exactly correct.  

73, k6gt

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