This tube, IN-5B-1, is very special: it has the same small shape of the IN-2 tube with a different socket and is the twin of the IN-5A-1 tube which has only three symbols as this model. It has a ‘Y’, an ‘S’ and a ‘y’.
|symbols||-||S, Y, y|
|dimensions||mm||⌀ 8 x 40|
|socket or alternative||-||7 pin miniature socket|