I'm wondering what effects does low emission capability have on tubes. It's obvious that with lower emissions the maximum cathode current is reduced. What else changes? Mainly my concern is plate resistance and thus the curves.
Is there any difference with low emissions from age and wear, or low emissions on account of sub spec heater voltage?
Are curves measured in a low emission situation reliable (at least at lower cathode currents)?
Is there any difference with low emissions from age and wear, or low emissions on account of sub spec heater voltage?
Are curves measured in a low emission situation reliable (at least at lower cathode currents)?
Low emission is likely to mean that current and gm go down. As mu will remain largely unchanged, the anode impedance will rise. This means that, on average, a triode circuit will survive valve ageing better than a pentode circuit - triode amplification is largely set by mu, but pentode amplification largely by gm.
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