In the 1920's, radio was still mainly for the dedicated few. The receivers were large, clunky, hard to adjust, and heavy … and aside from "crystal sets," they were all battery-powered. All receivers used tubes, and the tubes needed the dreaded "A" and "B" batteries. (The 6-Volt "A" battery was for the tubes' filaments; the plate supply was formed of 45-Volt "B" batteries. And yes, this is where the name "B+" for the plate supply came from.) Along came Edward Rogers (senior), boy genius, who brought not one but two technical innovations to radio receivers, that made them much, much more accessible to the general public. As it turned out, he was just getting started.
First, the A Supply.
Ted invented the indirectly-heated cathode, that
meant that the filaments could be powered from AC power. Since there were several tubes needed in the
receiver, if you were clever you could then place all the filaments in series
and power them directly from the 120-Volt mains.
Why didn't someone else try this? Well, they did, but with the regular tubes of the day, the AC hum from the filaments would come out the other end of the radio a lot better than did the intended signal. Ted's genius idea was to stop using the filament as a supply of free electrons, and instead use it as a heater for an electron-generator. His cathode was a specially-treated sleeve that slid over the filament heater. By its design, it shielded the cathode and the rest of the tube from the AC fields generated by the filament inside. The result: no hum!
Next, the high-voltage or B Supply.
result was a console radio, with a loudspeaker, that wasn't continuously
draining big, heavy, expensive batteries when it was being used. Ted Rogers, with his brother Elsworth, and financial backing from his father, started
the Standard Radio Manufacturing Company (later Rogers Majestic), which begot the
Rogers Radio Tube Company, which led to the Rogers Batteryless
Radio Company. In August, 1925,
1925 until 1927, the only batteryless radio receivers
on the market--anywhere--came from the