Hi All! Hopefully the ECS 12.09 CD does not have to be used. Since the ECS 12.09 crystal from the BFO mod seems to be very stable, I doubt if replacing the crystal with the CD type is necessary. By the way I have not seen any drift greater than 20 Hz from startup to operating 40 watts. Excellent stability now! 73, Rod WA9GQT K2 # 1900 KPA100