Down the Rabbit Hole
Restoring the Freshman Masterpiece AM radio was a lot of fun, but using batteries wasn’t. They’re convenient for testing, but expensive for regular use. The “B” battery alone uses ten 9-volt batteries, and that’s over $20 per set. There are battery simulators available for old tube radios, but they’re not cheap either, and where’s the fun in just buying a plug-in power supply? Wouldn’t it be cooler to use solar power and a 12-volt rechargeable battery?
I mentioned finding two old 20’s-era broadcast receivers in an earlier post. Some months had passed, and restoring the Freshman Masterpiece “5F5” seemed like a fun project and a quick win. The radio was designed to run on two batteries: an “A” or 6-volt battery for the tube filaments and a “B” or 90-volt battery for the plate voltage.
Funny how things come full circle. When I was a young electronics experimenter, tube equipment was cheap and solid state devices were expensive and exotic. I could work with low-power diodes and transistors, but to accomplish anything with some power, tube circuits were king.
About 40 years ago, Bob (a high-school buddy) and I started a surplus electronics business. We were hoping to make a little extra money and feed our Amateur Radio habit. We started with a purchase of 18,000 pounds of stuff.