16-04-2017, 04:10 PM
Hi Mark
It would have helped it I had read the manufacturers notes, which I was doing whilst you posted.
They dont say specifically that TX7 is the FM oscillator, but they do describe TX8 as being controlled by the voltage from the FM ratio detector, and that TX8 is part of the AFC circuit, its degree of conductance alters the effect of C49 across L29, and hence gives an AFC control of the oscillator..
So you are correct.
Hmm, time for some more voltage checks and then try with a 10.7MHz FM signal to see how far forward through the circiut I can go with that.
For some strange reason my repaired/modified Leader signal gen has stopped giving a modulated signal, so its get the massive old Advance out and warm it up.
I wonder is this the first ALL silicon FM portable with AFC.
I wish I could find a circuit diagram for the predecessor of this radio, the KB KR017. It would be interesting to compare with this radio. The KR017 only has 9 transistors so it must be missing the AFC function.
Mike
It would have helped it I had read the manufacturers notes, which I was doing whilst you posted.
They dont say specifically that TX7 is the FM oscillator, but they do describe TX8 as being controlled by the voltage from the FM ratio detector, and that TX8 is part of the AFC circuit, its degree of conductance alters the effect of C49 across L29, and hence gives an AFC control of the oscillator..
So you are correct.
Hmm, time for some more voltage checks and then try with a 10.7MHz FM signal to see how far forward through the circiut I can go with that.
For some strange reason my repaired/modified Leader signal gen has stopped giving a modulated signal, so its get the massive old Advance out and warm it up.
I wonder is this the first ALL silicon FM portable with AFC.
I wish I could find a circuit diagram for the predecessor of this radio, the KB KR017. It would be interesting to compare with this radio. The KR017 only has 9 transistors so it must be missing the AFC function.
Mike
