Tube cross-reference
81421 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 81421 specialized - photo tube. Compare core specifications and verify every restriction before using a replacement.
No alternatives recorded
Tube Tinker does not currently have an exact variation or directional substitution recorded for 81421.
Verify before substituting
Matching a base or heater voltage is not enough to prove that two tubes are interchangeable. Check pin connections, heater current, maximum ratings, bias requirements, warm-up behavior, and the equipment manufacturer’s service documentation before making a substitution.
View the complete 81421 specifications →