PRS-100 (190-0900) Hints and Tips Faxback Doc. # 17141 Availability of new Crystals: Call Hy-Q International at (606) 283-5000 or another Vendor of your choice. Crystals are in a "UM-1" package. RX Crystal frequency = Desired frequency - 21.4 MHz / 9 TX Crystal frequency = Desired frequency / 27 Have a radio technician install and align as per Service manual which is available from Tandy National Parts, Part # MS1900900.