[Amps] 2879 biasing

[Bill Eitner]

> >2 wrote:
> >>
> >> >When adjusting the bias for a 2sc2879 amp operating at 15v, what
should the
> >> >resting collector current be for reasonably linear operation?  I've
seen
> >> >values
> >> >suggested that range from 100 to 200 ma per transistor.
> >> >
> >> I use 200 per.
> >
> >Hi Rich,
> >
> >Just to be 100% sure -- since most of these amps have boards with a pair
of
> >transistors -- do you mean 200 per TRANSISTOR or 200 per BOARD?
> >
> The mfg of the radio said 200 for a pair.  That was not clean enough, so
> I went with 200mA ea.
> cheers, Vic

    What was the flange temperature?

    Remember that unless you're using a temperature
    compensating bias circuit the resting collector current
    will rise as the heatsink, flange, and B-E junction(s)
    increase in temperature.  In a nutshell, what is Class B
    and a little dirty at room temperature can quickly become
    Class AB and clean after the first QSO--especially with
    15 volts on the collector(s).
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 -=[Bill Eitner]=-

Link to A.M. Tutorial and rec.radio.cb FAQ:
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