01-09-2011, 08:21 PM
Victory!
The suggestion to look at the cathode voltage on the 6k7 made me notice a resistor+capacitor combination that I had replaced. The schematic read 400 ohms. the resistor read 400k ohms. Clearly I grabbed the wrong one. Swapping that resistor out for a 400 ohm got me very very quiet audio! (and took the cathode voltage from ~15v to ~1.5v).
However the audio was indeed quite quiet and the volume control didn't work. A couple hours of head scratching and wire tracing led me to the discovery that the wiper on the volume was not connected to the grid on the 6q7 like the schematic indicated! It was connected to one of the diode plates in that tube instead. Moving it to the right place resulted in a working volume control and good loud audio!
I've listened to it for a couple hours now and it seems to be working reasonably well. The dial scale is not accurate. I guess i'll have to figure out how to align it. All three bands work, though sometimes when switching between them nothing will come in (not even static) until power cycling the whole radio. No idea what that means.
One worry I have is that the output tube (6f6) runs very hot. It is a metal tube so I can't tell anything visually. The voltages match the rider. So maybe that one just runs hot?
Thanks for everyone's help! This forum is a great resource!
The suggestion to look at the cathode voltage on the 6k7 made me notice a resistor+capacitor combination that I had replaced. The schematic read 400 ohms. the resistor read 400k ohms. Clearly I grabbed the wrong one. Swapping that resistor out for a 400 ohm got me very very quiet audio! (and took the cathode voltage from ~15v to ~1.5v).
However the audio was indeed quite quiet and the volume control didn't work. A couple hours of head scratching and wire tracing led me to the discovery that the wiper on the volume was not connected to the grid on the 6q7 like the schematic indicated! It was connected to one of the diode plates in that tube instead. Moving it to the right place resulted in a working volume control and good loud audio!
I've listened to it for a couple hours now and it seems to be working reasonably well. The dial scale is not accurate. I guess i'll have to figure out how to align it. All three bands work, though sometimes when switching between them nothing will come in (not even static) until power cycling the whole radio. No idea what that means.
One worry I have is that the output tube (6f6) runs very hot. It is a metal tube so I can't tell anything visually. The voltages match the rider. So maybe that one just runs hot?
Thanks for everyone's help! This forum is a great resource!
