FFB ...
Very limiting with 10 Channels VHF at 25 Khz spacing ... I can't remember the formula now (perhaps Dan can ?) ... but quite easy to re-tune if you have an aerial coax connector with a low voltage bulb soldered across the contacts ... then tune the set with a new crystal indicated by the bulb glowing the brightest !
Of course that was for the Radio Tech to do
Coff.