need help on amplex radio

[prkohlwey]

does anyone have a schematic for a Amplex Lectro Sonic model C radio. Someone has don a hack job on this one and I am trying to restore it to somewhat original. I have not been able to find anything about these radios. It is a simple design but I would like to know what the cap values are and if the wiring is right. Any info would be appreciated.

[Reece]

I hadn't heard of it, but Googled the name: there were two Amplex companies in the twenties it seems, one out of NYC and another in Indiana, building typical twenties sets. Although from the model you mentioned is that a more modern radio?

[prkohlwey]

It is the one from New York. I believe it is a 28 or 29. It is a single dial with 0-100 dial. I do have the original paperwork with it and the warranty card but no schematics.

[Reece]

How many tubes? If there are three tuning condensers coupled mechanically together to one dial, I'm guessing it's a five tube TRF. The schematics for these were mostly very similar. On ones like this where I had no documentation I took the time to trace out and sketch and then draw the schematic and compare to schematics of similar sets. Usually the two RF stages are basically the same and then comes the detector which may only vary by having a grid condenser and grid leak, followed by a couple of audio stages usually with interstage transformers, which "like" to be open. The sets don't tend to have many fixed passive components. Sometimes when drawing out the schematic and then looking at it logically you'll see where somebody "fixed" it in the past.

[prkohlwey]

It is a 7 tube set if you count the rectifier tube. It has its own power supply with an 80 tube. The others are 3-26 tubes for the stages one 27 tube and another 26 then a 71. The audios test out good.

[Reece]

Aha, so it's in the late twenties when AC sets became available. The 26, 27, and 80 were introduced in 1927.