Symbol Description

U a Anode voltage at operating point.

I a Anode current at operating point.

U g Bias voltage (grid voltage) at operating point.

R i Plate (internal) resistance at operating point.

R a Plate load resistance.

S Transconductance calculated at operating point.

µ Amplification factor of a tube at operating point.

P a Anode power dissipation at operating point.

I s Screen grid current (tetrodes and pentodes).

P s Screen grid power dissiparion at operating point.

R k Cathode resistor.

P rk Power dissipation of cathode resistor.

G (rk) Gain of a single stage amplifier with cathode resistor.

G (rk=0) Gain of a single stage amplifier without or bypassed cathode resistor.

M L Lower frequency distortion at frequency F L

M H Higher frequency distortion at frequency F H

P out(t) Power dissipated in the anode circuit of SE amplifier

P out Output power (SE) - P out(t) corrected by transformer efficiency

η Output transformer efficiency (usually in the range from 0.8 to 0.9)

L 1min Minimum inductance of the primary winding of output transformer

L 1smax Maximum leakage inductance of the primary winding of output transformer