Vintage 1946 Sonora AM Radio Restoration – 04 – The Plan


Coming up with a plan:

At this point I knew that the radio was missing some key components on the outside (primarily the dial scale), and I figured that it would be almost impossible to find original replacement parts for it. So, some of this restoration was going to be made up as I went along. That got me to thinking about what else I would like to do to the radio on top of restoring it to its original working order. This is where the term “Resto-mod” comes into play instead of just “Restoration”. Resto-mod is a term I have seen used in restoring old vehicles when someone takes an old car, restores it back to original condition for the most part but modifies it to add some additional desired features like a different engine or transmission, etc. I still wanted to keep the radio as original as possible but since this was my Grandparents old radio, and it was a radio that was sold during a very cool time in history, I decided I would keep it as original as I could but add some hidden bells and whistles to it without destroying any of the original pieces.

But the gears in my head were already turning! I thought about how cool it would be to be able to turn on the radio and then “tune in” some old radio broadcasts from the time that this radio was new! To be able turn it on and listed to some Big Band music or Bing Crosby, Glen Miller, and The Andrews Sisters. How cool would it be if I could tune in a station where I could hear news bulletins from that time frame? News bulletins from the time of World War II! Or even listen to some of the old radio shows like the famous broadcast of Orson Wells’ – War of the Worlds or Jack Benny, or Superman, or Tales of the Texas Rangers, or the Bob Hope Show!? Some more research was in order! And a quick search of the internet told me that at least I could download MP3 or WAV recordings of some of these old shows. And of course you can still purchase some of this music online! So now it was just a matter of figuring out a way to make all of that work!

I knew that I could create a low power AM transmitter and just tune in a specific station on the radio to listen to it, but I wanted more than one station. Good AM radio stations are sort of getting scarce as it is and I wanted to able to tune in several stations across the dial and play specific things for each station. And I CERTAINLY did not want to have to build several AM transmitters to do this! Besides the fact that I wanted to be able to make it portable also if wanted to take it to another location to listen to. So a “smart” MP3 Player was in order!

So… I began to think of how I could figure out a way to tie in a microprocessor (Arduino board) programmed as an MP3 player and be able to add maybe 4 or 5 “Stations” that could be tuned in that would play period correct news and music! What was really cool about that idea is that the sound would be piped through an old two stage tube amplifier in the radio and would get that great great sound that only a tube amp can give! But, I knew I had to make it all seamless! I wanted it to seem like the added “Stations” were being “tuned in” as opposed to going the easy route and adding switches to flip over to an auxiliary input for the MP3 player or using a limited AM transmitter to be able to tune the dial to it for reception! What fun is that? πŸ˜‰ None of that was not going to be an easy task by any means, but I have always enjoyed a challenge! πŸ˜‰ And it would be something I could add once I had the original radio restored to working condition and had it looking nice! πŸ™‚ I was also going to have to figure out how I was going to make a new dial scale and put that scale on a piece of glass or acrylic, and then fashion a frame to mount the dial scale on the radio in the original location. But again, that part could come after I had it working once again.

So, turning my attention to the electronics, one thing I new for certain that I would have to do to get this working was to replace pretty much all of the capacitors in the radio. Capacitors made during that time frame were simply not made to last for almost 70 years! These old capacitors were made of foil and paper and wrapped in wax and when you add high voltage electricity to something like that that might be ready to fail, you are just asking for it to catch fire and try to burn your house down! This is why you don’t want to turn an old radio on like this unless you KNOW what you are doing! So my plan was to get rid of all of those types of capacitors and replace them with new components to not only remove the hazards, but make the radio more reliable as well! Most of the other components in an old radio like this will be fine and you can leave the old ones in the unit. Resistors, coils, switches, and other components were built very solid back then and don’t really deteriorate much with time. You will only run into some parts like these that might need replacing every now and then. Or you might need to replace something if it had been modified by someone else in the past and needs to be replaced to get it back to the original condition again.

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