The 6AL5 (European type EAA91 or EB91) is a high-perveance dual diode vacuum tube with a 6.3 V, 0.3 A heater.
The 12AL5 (European type HAA91) is the same but has a 12.6 V, 0.15 A heater. Both have a B9A (Noval) miniature 9-pin base.
The 6AL5/12AL5 serves as the as the "disconnect diode" in the timebase circuit of many tube-era Tektronix scopes starting with the 511 in the 1940's and continuing through the 1960's in sweep plug-ins such as the 3B2 and other plug-ins such as Type C/Type CA.
Tek part number: 154-0016-00 (6AL5), 154-0038-00 (12AL5/HAA91)
|Aged/Checked/Matched Pair Details|
|Used in||Tek Part#||S/N Range|
|535A, 545A, 585A||157-0075-00 (12AL5)||All|
|316, 317, 502A, 516||157-0104-00 (6AL5)||All|
|53X, 54X series, 551, 580||157-0104-02 (6AL5)||All|