11-13-2011, 03:31 PM
I am starting on a Philco 70A (serial number: 152093, no letter B). Circuit has been messed with but circuit layout and tube layout seems to match 70-A Below B-22000.
I have a couple of questions to get me started:
1. Original speaker is trashed. Shredded field coil, bad output transformer. I'm thinking I'm going to have to use an 8" PM speaker that I have along with a roughly 3000 ohm 10-20 watt resistor to replace the field coil. Perhaps eventually I'll find a Philco 70 speaker.
2. The power transfomer for a 70-A is supposed to be for 25-40 cycle current. Do I have to worry about using it with our 60 cycle current?
Thanks for you help in getting me started on this project.
Mark
I have a couple of questions to get me started:
1. Original speaker is trashed. Shredded field coil, bad output transformer. I'm thinking I'm going to have to use an 8" PM speaker that I have along with a roughly 3000 ohm 10-20 watt resistor to replace the field coil. Perhaps eventually I'll find a Philco 70 speaker.
2. The power transfomer for a 70-A is supposed to be for 25-40 cycle current. Do I have to worry about using it with our 60 cycle current?
Thanks for you help in getting me started on this project.
Mark
