Tachyon Cannon

Who do tachyon cannon barbettes work and at what tonnage can a ship have barbettes?
Except in the High Guard 2022 update , a barbette now needs 3 firmpoints, so that requires a 70 ton ship. In both versions, on craft less than 100 tons (i.e. on a firmpoint as opposed to a hardpoint), the weapon is also limited to Close range.