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Jon_G4MDC · 6th Sep 2019, 2:07 pm

PF1 TX is fundamental ~12MHz so parallel and 30pF loading is probably OK.
Fx=Ftx/36
RX is 5th Overtone ~85MHz and series resonant.
Fx= (Frx-10.7)/5

PF9 is much more difficult - AFC on RX and direct FM on TX means the pulling characteristics matter. I think they are 3rd overtone and series resonant but there is more to it than that.
Due to the AFC you can't swap sides with the LO, it has to be Fc-10.7MHz. If you try Fc+10.7 the AFC runs away from the signals. Been there tried that.

6th Sep 2019, 2:07 pm	#2
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Pye PocketFone crystal spec? PF1 TX is fundamental ~12MHz so parallel and 30pF loading is probably OK. Fx=Ftx/36 RX is 5th Overtone ~85MHz and series resonant. Fx= (Frx-10.7)/5 PF9 is much more difficult - AFC on RX and direct FM on TX means the pulling characteristics matter. I think they are 3rd overtone and series resonant but there is more to it than that. Due to the AFC you can't swap sides with the LO, it has to be Fc-10.7MHz. If you try Fc+10.7 the AFC runs away from the signals. Been there tried that. Last edited by Jon_G4MDC; 6th Sep 2019 at 2:14 pm.