gener-raco: Likely battery type for General Radio 174B

Inside the wooden housing of the GR 174B wavemeter is a square bracket and spring contacts surrounding an obvious space for a battery.  In the 1920's, the Eveready 771 "C" battery measured 4" wide, 3" tall and 1.3" deep.  It exactly fits the space, and the 4.5 V is about right to drive the buzzer.  The 771 was a very common battery back then, and I could find no other battery that even came close to the right size and voltage.  Most 771 batteries came with Fahrensotck clip connectors, but I think there were versions with simple flat contacts.  So, I think it is pretty obvious that the GR 174B used a 4.5V Eveready 771 battery.  BTW it's very easy to 3D print or otherwise construct a box of the right size and stuff it with 3 or 6 modern C batteries.  

• Replica 771 in GR 174B housing (251 KB)

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