Tube cross-reference
LL521 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the LL521 new (being researched). Compare core specifications and verify every restriction before using a replacement.
Exact variations of LL521
These designations belong to the same electrical variation group. Their names may differ because of international standards, manufacturing tolerances, or materials, but they are recorded as electrically equivalent—not merely substitutes.
21KQ6 Power - TV Horizontal Output (sweep)
- Base
- 40A
- Socket
- B12C
- Base pins
- 12
- Sections
- 1
- Heater voltage
- 21.5 V
- Heater current
- 0.45 A
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 LL521 specifications →