This pickup came out of a 1960 Rickenbacker Steel Guitar which I replaced the pickup in, in an essence of time for the customer, ...knowing I can rebuild the broken bobbin top on this one as casual bench time might allow.
It is of the mid-late 1950's stock as evidenced by:
(1) The rounded bakelite bobbin extends well beyond the coil. Later post-early 1960's Rickenbacker
horseshoe pickups utilized plastic bobbins.
(2) The pole pieces are the old style and not the screw-heads of the later plastic bobbins.
(3) The coil measures approximately 2.5K ohms; Signifying that it is wound with the thicker (#38?) mid-late 1950's
wire rather than the thinner (#42) post-early 1960's wire that measured 6K ohms or more.
(4) The magnet is still strong, as opposed to a later 1960's whose magnets were of an alloy meant to take a smaller "charge".
NOTE: Rickenbacker apparantly started running out of the bakelite bobbins in the early half of the 1960's. So they reconfigured the horseshoe pickup mainly to use on their bass guitars, and used them on the few Steels they continued making. The bobbin was thereafter made of plastic, the coil was wound with thinner wire, and the horseshoe magnet alloy was made to take a weaker "charge". The last Rickenbacker Steels were made in either 1973 by most sources and another reputable source saying they've seen a very rare 1974 Rickenbacker student model.
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