02-25-2018, 11:01 PM
Work has begun on the Radio. I liked the speaker so I decided to start there. It is a self powered, Jensen electrodynamic speaker with an AC switch to turn it off for whatever reason. I suspect it came from Jensen that way and Grebe just left it in. The full wave rectifier is, I presume, a copper oxide unit (selenium rectifiers were invented a bit later according to my research). It consists of 2 parallel, 2-discs in series units, for each diode in the full wave rectifier. (That's probably clear as mud!) I have not yet powered up the power transformer so i'm not sure of the operating voltage, but it must be fairly low. There is no filtration for the field supply, just a hum bucking coil. Question: who knows about copper oxide rectifiers? Are they safe to power up or do they exhibit the same potential problems as selenium rectifiers? I've only tested it with the diode testing portion of my fluke meter. Forward reading is about 10 times lower than reverse reading. How much reverse leakage is to be expected with copper oxide diodes? I have not been able to find a good answer by googling it.
The cone is in good shape but very fragile. Obviously, the edge surround need to be replaced. not sure what to do with that but will do some research. Any suggestions? Thanks in advance for any help you can give!
I thought the brown, paper tube would be just a capacitor. It's across the primary of the output TR. Damage was done in removing the assembly from the tube as it was encased in very hard tar. It turned out to be a .02mfd cap (measured, but not sure of the accuracy) in series with 180 turns of 38 awg wire wrapped around the cap, in series with another inductor of 2500 turns of 34awg wire round an iron core. I unwound it all to figure out what it was. Now I've got to wind it all up again (with new wire)! Interesting project.
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The cone is in good shape but very fragile. Obviously, the edge surround need to be replaced. not sure what to do with that but will do some research. Any suggestions? Thanks in advance for any help you can give!
I thought the brown, paper tube would be just a capacitor. It's across the primary of the output TR. Damage was done in removing the assembly from the tube as it was encased in very hard tar. It turned out to be a .02mfd cap (measured, but not sure of the accuracy) in series with 180 turns of 38 awg wire wrapped around the cap, in series with another inductor of 2500 turns of 34awg wire round an iron core. I unwound it all to figure out what it was. Now I've got to wind it all up again (with new wire)! Interesting project.
