19-03-2017, 10:55 AM
(19-03-2017, 01:50 AM)Nowhere-Man Wrote: "L23 is tertiary winding, it fits the bill as described in the books because it's tightly coupled to the transformers primary as indicated by the common tuning slug coupling it to the primary winding (L25) you can also see that the audio output on FM is taken from that via a simple filter network and ends up at switch contact 17."
Agreed. I located C51 and 17 switch contact. It's much better now I swatted up a bit, although I still need to keep redoing the schematic to consolidate it. Not sure about the AVG yet. The more I trace it through the clearer it gets bit by bit.
The AGC rail is reasonably easy to trace, as said earlier the AM detector diode in the EBF89 supplies the AGC voltage and also the voltage for the grid of the tuning indicator, the voltage for the grid of the tuning indicator is supplied via R41, the AGC line voltage is supplied via R21, if you follow the AGC line through you'll see that it is, in effect, connected to the control grid's of the Mixer and the IF amplifier valves, more -ve means less gain.
Lawrence.
