[AMPS] Re: 8877

Sat, 26 Jul 1997 21:55:43 +0000

> From:          Rich Measures <measures@vc.net>
> Date:          Sat, 26 Jul 97 04:42:13 +0000

> >Of course youn forgot to mention when the tube is neutralized, the 
> >anode grid capacitance effectively goes to zero.
> >
> Good point, Mr. Rauch.  Nevertheless 1000v of grid drive across a 100pF 
> grid takes a bit of doing.

Rich, I have to question your motives. People ask for help, and you 
go on and on with home made non-sense. Take, for example, the 
poor guy who asked about an ALC system question and you posted some 
made up implication about plate current affecting it.

Look at this silly 8877 series of posts. I assume you are still 
talking about a 3CX2500 or 3000 series tube. First you "forget" the 
fact if the tube is neutralized, it has effectively no anode to grid 
C.

Next you make the filament to grid C 100 pF, instead of the ~30 pF 
it really is.

So now, in your fifty-two post response to a single simple 
question (that you never really helped the poor guy with) you want 
us to all accept the fact we can't drive a 30 pF (~150 ohm) grid with 
1000 volts PEAK of  28 MHz RF.

Honestly, do you think the nonsense claims you make and arguing  
you do is being helpful?

> >Interesting you know the IMD level of amps from the 60's and 
> >earlier, yet when you discuss your big grid driven 13 kW PA you 
> >quantify IMD via over the air reports
> >
> I measured the total IMD of the 8171 Class AB1 amplifier with the 
> step-attentuator method, using H-P 355 step-attentuators.  

You used the subjective statement like this: 
"W6 ? told me my amp splattered on 40 meters when 
it showed grid current."  Yet  Ian, Peter, Carl, myself 
and others gave objective IMD numbers.

The first IMD numbers you gave were "guesses" at the IMD level of the 
811's and such.

I'm sure you actually believe you made measurements.

But IMHO, anyone who actually made measurements would have posted 
those objective quantitive measurements first, rather than posting 
some approximate guesses so late in the game.

73, Tom W8JI 

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