In fact, one of the first CK-722s that I took apart did have a smaller hearing aid type transistor inside. Later CK-722s were of course built as CK-722s and even later they were in black but somewhat clear epoxy cases. - 73 - Mike
Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Tuesday, April 20, 2010 9:57 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] And you thought you were old Do you know the story of the CK722? In the 1950s, Raytheon was making tiny transistors for hearing aids to replace the pre-WW II subminiature tubes. Aside: Those tubes, developed by Norm Krim, were ruggedized and used in the WW II Proximity Fuzes, one of THE big inventions of WW II. Anyway, Raytheon was making piles of these tiny transistors, but many were not making hearing aid specs. Norm got the idea of packaging them to sell to hams to learn about transistors. If you open up one of the blue ones, there is another tiny case inside which is the real transistor. BTW, Norm is still alive and well in his 90s. -John =============== > Anyone remember the CK722 transistor? As I remember they were about $7.50, > a > considerable sum. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.