Paul, A 60 MHz xtal oscillator divided by 12 and comparedwith the incoming 5 MHz. Then there is this thing how to acheive a good symmetrical FM injecting the 137 Hz signal without affecting the loop filterparameters.
Keeping the original design with modern typesof semiconductors is less work/effort, provided that the unit keeps working... The A7 original design used a non selective2nd harmonic detector. And uA 709's.That one was easy to motivate an upgrade. I am a bit lazy otherwise. As mentioned, the semiconductors that have failed in A3 were all dated 1968. At the time without knowing the exact types of the JFET'sI replaced them with 2N4416 only to discoverthat that was the type HP specified in a laterrevision of the A3. Best Regards Ulf Kylenfall _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
