Application note:
This tube can be used without precautions against microphony in equipment which is characterized by
Vi ≥ 10mV for an output of 50mW (or Vi ≥ 100mV for 5W output), provided that average acceleration of the
tube is not greater than indicated in the Section "Microphonic effect" from the "Application directions". In this
case the disturbance level for hum and noise will be better than -60dB when the center tap of the heater has
been grounded, Rg≤0,5MΩ and Rk is sufficiently decoupled.