The 1N270 Diode is another diode used in Crystal Radio sets ( Xtal Radio Sets ). It is made of a material called germanium a material used for transistors and diodes as one of the first semiconductors materials used commercially. These diodes are becoming hard to find I try to keep in stock around 1000 at all times.
Some places are selling silicon diodes as a substitute or equivalent replacement with the 1N270 number as germanium. Some of there data sheets even say germanium in the header but state silicon in the data area. Mine are germanium point contact diodes and not Schottky Silicon Diode.
The 1N270 Diode and a ceramic earphone and a tuning coil are all that is needed to make a simple crystal radio set ( Xtal Radio Set ).
The 1N270 Germanium diode can carry 100 volts 40 ma and the 1N34A can handle 65 volts and 50 ma and the 1N60 can handle 45 volts 50 ma if my data is correct.
The 1N270 Germanium Diode is used in many Ham Radio and Amateur Radio circuits as detectors and up converters, down converters ( Mixers ). Input shunts to protect equipment from overload.
The 1N270 Diode is also very popular in sound effect circuits like Guitar pedals.