were gradually pushed upwards by such features as thicker plates, grids of larger diameter wire, grid cooling fins, ultra-black plate coatings and low loss materials for the base. Variants of the 6L6 included the 6L6G, 6L6GX, 6L6GA, 6L6GAY, 6L6GB, 5932/6L6WGA and the 6L6GC. All variants after the original 6L6 utilized glass envelopes. A "W" in the descriptor identified the tube as designed to withstand greater vibration and impact. A "Y" in the descriptor indicated that the insulating material of the base was Micanol. Application The high transconductance and high plate resistance of the 6L6 requires circuit design that incorporates topologies and components that smooth out the frequency response, suppress voltage transients and prevent spurious oscillation. Characteristics Improved substitute 5881 Similar tubes 6P3S (6П3С) 6P3S-E (6П3С-E) 7027a See also 6V6 KT66 KT88 6550 6CA7 EL34 List of vacuum tubes References External links TDSL Tube data [6L6] Electron Tube Data sheets: Several 6L6 datasheets from various manufacturers Reviews of 6L6 tubes Vacuum tubes Guitar amplification tubes Telecommunications-related introductions in 1936