12-08-2019, 07:37 AM
(This post was last modified: 12-08-2019, 07:43 AM by Mike Watterson.)
OK , so 1 is capacitor isolated audio feedback (only connected when Modulation is on), 2 is HT and 4 is Audio triode anode. The CW position will allow external modulation.
5 & 6 then modulate the HT / RF on the RF osc. (70V HT and anode).
That makes sense of the transformer winding resistances and the only difference from 65 is the HT common on winding feeding grid (using capacitor isolation) vs ground referenced. AC wise it's the same arrangement as the 65.
So the Mod/CW switch somehow connects the feedback to the grid. The external audio in socket (if fitted, I forget), may go to the common of switch via a pot and thence to grid via a capacitor, mine has the socket always connected and that can give a low level audio out on the Mod position.
Perhaps the model 60 was short lived or for a particular military customer. I think the 65 came out in 1943?
5 & 6 then modulate the HT / RF on the RF osc. (70V HT and anode).
That makes sense of the transformer winding resistances and the only difference from 65 is the HT common on winding feeding grid (using capacitor isolation) vs ground referenced. AC wise it's the same arrangement as the 65.
So the Mod/CW switch somehow connects the feedback to the grid. The external audio in socket (if fitted, I forget), may go to the common of switch via a pot and thence to grid via a capacitor, mine has the socket always connected and that can give a low level audio out on the Mod position.
Perhaps the model 60 was short lived or for a particular military customer. I think the 65 came out in 1943?
