09-16-2013, 09:00 PM
Well, here goes....
I started on it today. I am not in any rush, will take my time.
As I wrote before, the ballast tube, despite its rusty looks, is actually fine.
Need to clean it up with something that would remove the rust.
The radio was repaired before, hence the two DC filter electrolytics missing - replaced beneath with tubulars. One of the electrolytics, the one that is not used in the DC filter, is still conencted. All tubular paper caps are original, though 3 or 4 have been replaced.
Now, the speaker: the output xfmr is there, but the speaker is a PM, a new type, probably 50-s / 60-s.
In the schematic the field coil is plugged as a load - in parallel to the B+ voltage and is not used as filter, there is a separate choke for that.
Now this got me thinking: I do not know if the Field Coil was enough of a load to somewhat lower the DC (B+) voltage, and if it was, then I might be running at a higher voltage. Which probably is not good. I would not know that without knowing what resistance the Field Coil was.
I also do not know what voice coil impedance is expected from the original speaker and whether the new one I have is the same.
Good thing, since the voice coil is not used as a filter I do not have to come up with stupid things like replacing it with ballast resistors etc.
Well, here's the start.
If someone has the info on my questions - could use help here.
I started on it today. I am not in any rush, will take my time.
As I wrote before, the ballast tube, despite its rusty looks, is actually fine.
Need to clean it up with something that would remove the rust.
The radio was repaired before, hence the two DC filter electrolytics missing - replaced beneath with tubulars. One of the electrolytics, the one that is not used in the DC filter, is still conencted. All tubular paper caps are original, though 3 or 4 have been replaced.
Now, the speaker: the output xfmr is there, but the speaker is a PM, a new type, probably 50-s / 60-s.
In the schematic the field coil is plugged as a load - in parallel to the B+ voltage and is not used as filter, there is a separate choke for that.
Now this got me thinking: I do not know if the Field Coil was enough of a load to somewhat lower the DC (B+) voltage, and if it was, then I might be running at a higher voltage. Which probably is not good. I would not know that without knowing what resistance the Field Coil was.
I also do not know what voice coil impedance is expected from the original speaker and whether the new one I have is the same.
Good thing, since the voice coil is not used as a filter I do not have to come up with stupid things like replacing it with ballast resistors etc.
Well, here's the start.
If someone has the info on my questions - could use help here.
