10-24-2015, 11:46 PM
(10-24-2015, 11:01 PM)Steve Davis Wrote: It looks the problem is after the 24 but before the 27. It could be lead dress. Try moving the 27 grid lead to see if that makes a difference.
Steve
I have already thought about that. In fact I changed out the lead from the .01 coupling capacitor block and the grid of the 27. I tried moving it around first, nothing really changed. I think the problem is the fact that the grid of the 27 is running at -7VDC, which is far too high for this tube. One person told me to try different values of grid bias resistors to lower it. However why, what caused the voltage to get so high in the first place? Further proof is when I put a small electrolytic with the + end to ground and the - end to the grid, the hum drops and I can hear the station to which the radio is tuned. However the capacitor does drop the volume to a low level at the same time it removes the hum. I was suspecting the voltage divider/bias resistor, but disconnected all of the terminals and checked the resistance and all sections tested correct according to the Philco schematic. Tubesforme
