This is a diagram of a commercial radio from 1946. The configuration is a transformerless source with the filaments connected in series. The 5-tube circuit uses a loop antenna and tunes to the mid-wave band.

This is a diagram of a commercial radio from 1946. The configuration is a transformerless source with the filaments connected in series. The 5-tube circuit uses a loop antenna and tunes to the mid-wave band.