[R-390] R390A audio amplifier

[Eric Gauja]

Dear Group Members,
                                     I have a question about the R390A audio stage.  The AF cathode follower V601B is connected to the grid of the local or line AF amplifiers V602A  , V602B  through the volume control pots R105 and R104.   The receiver can be muted by the break-in relay switch connecting the cathode follower cathode resistor R627 to ground.  Complete silence.  Operation of the break –in switch once more restores audio.  Good.   However, if the gain volume control pot is turned to its minimum position, there is still audio present at a low, but noticeable level.  Why does this happen? At the gain control’s minimum position, is not the grid of the AF amp connected to ground also?    

Best Wishes from Eric (Sydney, Australia)