I just measured the voltage drop across the selenium stack in one of my TransOceanics. Sorry I couldn't get to it sooner, but I have a 2-year-old running around these days so hobby projects go much slower.The stack in my radio has six plates. Input voltage measured 122vrms and the output was 107v. Not a real scientific test, since I didn't measure current and didn't take into account the fact that half-wave rectification cuts one-half cycle. But it does give you an idea of the scale.