Yes, the receiver can be crystal controlled if necessary. - Al On 9/13/2011 6:49 PM, Bry Carling wrote: > Great information on the GRC109, Greg. Does anyone know what the "CRYSTAL" socket > (with a screwed-on metal cover) on the front of the "reciever" is for? > tml -- Al Klase - N3FRQ Jersey City, NJ http://www.skywaves.ar88.net/