Gertch used injection lock for years on their frequency meters. Had
several good papers on the operation. I used a 100 kc xtal to "Jam"
lock the LO on FM tuners for years in My frequency measuring service.
Back when stations subscribed to a service on a monthly basis. Basicly
I have divided down to 10 kc then "Jam" locked LO's at the broadcast
band also. Regards, Sparks Broadcast Consultant