12-06-2023, 11:16 AM
I spent the last two days with my eternal Philco 650 project, assembling parts from two other chassis. Wired in the good wirewound bias resistor then did a check of the last few resistors and came across a cathode bias resistor that measured 400 ohms when it should be 300. Since it is a wirewound, I lifted one end and measured again, 292 this time. What's with that? Looked at the ground connection of the resistor and found a ground terminal attached to the socket rivet soldered to the cathode terminal. Put one multimeter lead on chassis ground and the other on the cathode terminal and the reading was floating around between 100 ohms and 100K ohms depending on how hard I pressed on the rivet. Fixed that and 3 others with solid wire soldered to chassis.
So now I have fired up the audio section and have it singing from the Phranken speaker I assembled from three. Original frame, cone & voice coil from an exact 650 duplicate and OT from a Philco of 30s vintage. On to the tuning cap and rf section.
So now I have fired up the audio section and have it singing from the Phranken speaker I assembled from three. Original frame, cone & voice coil from an exact 650 duplicate and OT from a Philco of 30s vintage. On to the tuning cap and rf section.