FT-243 crystals have pins spaced 1/2 inch apart, and are used in MANY ham radios made from
the 1940s through 1970s. They are also used in countless military sets such as the BC-611, TRC-77 and GRC-109 etc.
Note: Some of these are original FT243 crystals, some are reworked surplus units with
wire lead crystals inside as described in tube transmitter articles using them in CQ Magazine
and detailed technical analysis in Electric Radio Magazine.