Author: Alan, 5B4AHJ
The JB prefix, excluding JB8, has never been used,
The JB8 prefix was used for a few days in August, 1963, by a DXpedition to Torishima Island (not to be confused with Minami Torishima).
The JC prefix has never been used.
There are many callsigns with these prefixes in the Club Log QSO database. With the exception of the JB8 calls in 1963, these are all busted calls.
The majority of JB calls are busted YB calls, with a sprinkling of busted J6 & J8 calls.
The JC calls are busted JA, JH, JR, YC and other calls with similar prefixes.
Club Log maps these calls as follows:
JB8 - Japan from 1963-08-13 to 1963-08-18
JB - with the exception of the JB8 mapping above, all are mapped to INVALID for all dates
JC - INVALID for all dates.