John,
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Yes, your radio is as marked on the front panel just above the tuning dial, FT-101. The 101B was not introduced until early 1974 and these have FT-101B on the front panel.
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Yours is the correct supply connector as supplied by Yaesu. The same connector is required for operation from DC, but the wiring will be quite different. The details of the wiring of these connectors is shown on the schematics in the User Manual and Service Manuals.
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From your photo and list of connections for your AC supply cable it does appear to be correct, but do double check and compare to the data in the manuals.
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Your radio should be capable of operation from DC, BUT the switching transistors on the rear panel are prone to failure so be careful and make sure you have fuses of the correct rating fitted.
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73,
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Peter
G4DJB