Yaesu Rotators use English (Imperial) sized Ball Bearings. Depending on the specific rotator model, the size will be:

5/16" (7.938 mm) for elevation rotor of G-5500 http://ivok.home.xs4all.nl/pa1ivo/G-5500.html

3/8" (9.525 mm) 65 rockwell 65/35(steel/nickel) for azimuth rotor in larger G-1000 rotors

w9gb

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