NOS, TESTED, TELEFUNKEN AF137 GERMANIUM PNP TRANSISTOR TO REPLACE 2N990, 2S43, 2SA73, 2SA93, 2SA518, 3AG10, 3AG11, 3AG12, 3AG21, 3AG22, AF106, AF117, AF127, G106T, GF122, GF322A, GFT43, OC41, OC169, P416, ST28C, ST37E, T-1877, T-2091,
Availability: 90 in stock
Alas and alack, the fabled germanium alloy diffusion germanium transistors, the AF117. Mulalrd spent years oerfecting the zone refining of the germanium ingots to make the junction but then went and spoilt it all by placing the junction in a bed of silicon grease contained within a tin plated steel enclosure of the TO-7 style.
As years went by, the tin grew linear cystalline exflorations, colloquially known as whiskers which rather inconveniently shorted the junction. Some enterprising fellows devised a regimen to remove these whskers that ranged from smacking the TO-7 case with a hammer, heating it with a soldering iron, blasting 9 - 30VDC through a 100uF capacitor into the transistor to name but a few. These various approaches were hassle bound, prone to not working and a temporary measure to boot as the whiskers eventually grow back within a number of years again rendering the transistor useless all over again.
Wouldn't it be nice if you could get a germanium junction within a reliable enclosure and so it is that you can because our European buddies encapsulated a similar device in an enclosure that didn't suffer from tin whiskers and termed it the AF137- sensible fellows.
And... we have a small stock of these, made by Telefunken, individually tested, working fine and just the thing for repairing your wayward prized germanium transistor radio - simply super.