Sylvania Electric Products, Inc. AVT 21LR8 Vacuum Tube

The Sylvania AVT 21LR8 vacuum tube is a vintage nine-pin plug‑in device from Sylvania Electric Products, Inc., housed in a glass envelope. Classified in historical references as a triode‑beam power tube, the 21LR8 combines a triode section with a beam output stage in a single envelope for higher‑current amplification in mid‑century electronics. The product listing confirms a nine‑pin base and glass body, consistent with AVT‑series valves of the era. This tube is suitable for use as a power/driver element in vintage audio, video, or test equipment that relied on compact, high‑current vacuum tubes and nine‑pin sockets. When handling or replacing, exercise care with the glass envelope and ensure correct pinout and socket compatibility, as electrical characteristics can vary by specimen and vintage lot. Available from collectors and surplus suppliers, the AVT 21LR8 is documented in retro tube catalogs and reference guides as part of Sylvania’s line of vacuum tubes used in beam‑powered triode applications.