12-11-2022, 11:09 AM
I have 3 Radiola 18s, after replacing the volume control rheostat, one works well, so far, and I like the sound. I have 2 RCA 100 speakers that sound muffled. I looked at disassembling these to repair them, but the screws are frozen in the pot metal and have been damaged by someone earlier. I did look inside one speaker enclosure, the speaker mechanism looks interesting, but repairing these will need to wait. I have a nice 2K Ohm primary to 8 Ohm secondary transformer connected between the speaker output jacks on the Radiola 18 and a Jensen K950 PA speaker. In my opinion, the sound is remarkably good and clear for a 1928 radio. I suspect the Jensen speaker is fairly efficient and that this contributes to the sound quality. A few other speakers I tried were not nearly so good.
I've tried the 2 sets that don't work, the power supplies seem to be the problem. Rather than risk the one good set by using its PS to try the other 2 tuners, I've assembled a new power supply to try the two non-working tuners. It isn't wired yet, but is ready to be. This also seemed like a good way to learn about the way these sets work. I'm thinking that it might also be interesting to try building just the audio section of the tuner, the #26 & 71 tubes, and using a CD player, 78RPM turntable or other sources.
I have the Radiola Guy information and various other materials with schematics for the Radiola 18. I think I understand some of the circuit, and have been thinking it might be possible to assemble the section of the schematic including tube number 5(UX-226) & tube number 6(UX-171-A), and connecting the source(CD Player & Etc.) to the grid of the UX-226. I'm certain it's not quite that simple, and that additional circuitry is required. I also would need to know the specifications for the transformer between UX-226 and UX-171-A, and find a source for it. If anyone has suggestions for this project, I'd appreciate hearing these.
If there are other amplifier suggestions using different tubes that are compatible with the Radiola PS, I'm interested in that possibility as well.
I've tried the 2 sets that don't work, the power supplies seem to be the problem. Rather than risk the one good set by using its PS to try the other 2 tuners, I've assembled a new power supply to try the two non-working tuners. It isn't wired yet, but is ready to be. This also seemed like a good way to learn about the way these sets work. I'm thinking that it might also be interesting to try building just the audio section of the tuner, the #26 & 71 tubes, and using a CD player, 78RPM turntable or other sources.
I have the Radiola Guy information and various other materials with schematics for the Radiola 18. I think I understand some of the circuit, and have been thinking it might be possible to assemble the section of the schematic including tube number 5(UX-226) & tube number 6(UX-171-A), and connecting the source(CD Player & Etc.) to the grid of the UX-226. I'm certain it's not quite that simple, and that additional circuitry is required. I also would need to know the specifications for the transformer between UX-226 and UX-171-A, and find a source for it. If anyone has suggestions for this project, I'd appreciate hearing these.
If there are other amplifier suggestions using different tubes that are compatible with the Radiola PS, I'm interested in that possibility as well.
