Muirhead STD and REF cells - all catalogue info uploaded !. (AYCE)

[Assafl]

There is bittersweet irony in the K-231-A. From the Muirhead journal (1966) posted above by lowimpedance:



These were the last 3-4 years of a dying technology - trying to beat the Zener diodes coming from the semiconductor fabs.

To complete the Irony - the K-231-A (1967) has two Zeners in it to set the control threshold for the temperature regulation.