23-08-2019, 11:18 AM
The the -ve from the ratio detector to g3 is in effect FM AGC, the more -ve g3 is with respect to cathode the less the valve will conduct, it helps to prevent overloading of the ratio detector so far as I know.
I still think that the 300k is the main diode load for the AM detector but hey maybe that's just me.
Yet another example....Musikgerat 87....yep another three bottle reflexed FM job from Grundig but guess what...it has an extra switch to select between ratio detector (FM)
and AM...diode load is now totally obvious...yep, 270k, no more evidence needed with that one (click on thumbnail schematic):
https://www.doctsf.com/87-musikgerat/d36203/ref=20299
Lawrence
I still think that the 300k is the main diode load for the AM detector but hey maybe that's just me.
Yet another example....Musikgerat 87....yep another three bottle reflexed FM job from Grundig but guess what...it has an extra switch to select between ratio detector (FM)
and AM...diode load is now totally obvious...yep, 270k, no more evidence needed with that one (click on thumbnail schematic):
https://www.doctsf.com/87-musikgerat/d36203/ref=20299
Lawrence
