QST, Jun 1955, p. 88.
QST, Mar 1956, p. 93. (FO-1L)
First ad for International Crystal.
The FO-1 from the International Crystal Mfg. Co. was a printed-circuit-board crystal oscillator that could supply an accurate, stable signal between 1 and 15 MHz. Suggested uses were for net operations, as a frequency standard, or for close-to-the-band-edge transmissions.
