The Halcyon class was a class of 21 oil-fired minesweepers (officially, "fleet minesweeping sloops") built for the British Royal Navy between 1933 and 1939.
HMCS Caraquet (pennant J38) was a initially constructed for the Royal Navy during the Second World War.
The London and North Eastern Railway Class J38 was a class of steam locomotive designed for freight transport.
A telegraph key is a switching device used primarily to send Morse code.
The West Engineering XJ38 was a small turbojet engine created by modifying World War II-surplus aircraft engine turbosuperchargers.