[ARC Tech-109]

The mod was easy enough, just a couple of those wafer sockets and some thin wire. Follow the basic diode cathode & anode connections and find 6.3v to run the heaters. The thing about the 6AL5 is there is no junction "breakdown" voltage, they will forward conduct at once there is heat on the cathode with only a few pf of capacitance. The only downside if you will is the heater to cathode capacitance and the need to decouple the heater itself beyond a few MHz.

The real b**ch of the lightning strike is it was roughly a mile down the road but it followed the telephone trunk and found its ground at my QTH killing several pieces with the EMP as the Magnavox was not even connected to anything at the time, it took out all of the germaniums for the chroma, phase det and the diodes in the AM/FM stereo tuner (combo set)

There were a number of variations of those japanese germanium diodes, some had a low forward while others were twice as high being they were stacked internally. A silicon diode has a forward bias of 0.72v while germanium is 0.3v at its knee point, I don't recall the number for those glass diodes you have but they were like lice in the early 70's stuff from the likes of Panasonic... they were everywhere.

"Pure germanium is known to spontaneously extrude very long screw dislocations, referred to as germanium whiskers. The growth of these whiskers is one of the primary reasons for the failure of older diodes and transistors made from germanium, as, depending on what they eventually touch, they may lead to an electrical short." (Givargizov, E. I. (1972). "Morphology of Germanium Whiskers". Kristall und Technik. 7 (1–3): 37–41.)