I was always partial to the 6AL5 dual diode, which can handle over 300 volts: https://www.radiomuseum.org/tubes/tube_6al5.html https://www.radiomuseum.org/tube

I was always partial to the 6AL5 dual diode, which can handle over 300 volts: https://www.radiomuseum.org/tubes/tube_6al5.html https://www.radiomuseum.org/tubes/tube_6al5.html https://www.r-type.org/pdfs/6al5.pdf https://www.r-type.org/pdfs/6al5.pdf