Unit No.2 (high-mu section) has a maximum Rg of 0.5 MΩ for fixed-bias operation; this can increase to 1 MΩ provided plate-supply voltage and load resistance are such that plate dissipation does not exceed 0.5 W.
Maximum heater-cathode voltage: +/-275 V (peak) for Units 1 and 3; +/-200 V (peak) for Unit 2.
Maximum average cathode current is 20 mA per unit for Units 1 and 3 (no limit specified separately for Unit 2 — see max dissipation of 1 W).
Heater warm-up time (average) is 11 seconds.
No substitutes listed in TDSL or Brans. The 6U10 is a specialised TV compound type with no direct equivalents.