hi ampsters,
two questions occurred to me while catching up on
my e-mail reading:
1: "gain is mu*rp" ??? how??? gain is "mu" isn't it?
i.e. Vout/Vin = gain = mu;
or... gain = gm*rp, but not a mixture of the two!
gain is dimensionless: mu is dimensionless:
gm is a (trans)conductance with the units of inverse
ohms: rp is expressed in ohms: gm*rp = dimensionless
at least this is what i remember. i'm pretty sure
the laws of physics (even in tubes) haven't changed.
i'm *not* sure my recollection of the laws of physics
hasn't changed, however.
2: wouldn't a DC power supply like those used for
computers be a good filament source? with a little
tweaking and/or modification they could be set to
the factory's recommended voltage, and they would
act as a current source (at the limiting value for
the supply) and as the filament heated up, they
would change over to a regulated voltage. or is
the noise output of such a (typically switching)
supply just asking for another set of annoyances
when in receive mode? (even if we have the "perfect"
amplifier, we probably want to receive at least
*some* of the time!)
73,
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