The Ludlum Model 3 is quite a nice radiation meter, as long as you like analog displays and don’t mind it weighing one and a half kilograms: These can be found used for a reasonable price, are easy to fix, nearly indestructible, and have an adjustable HV power supply that will drive just about any Geiger tube or scintillation detector you can throw at it. Geiger tubes are mostly sensitive to alpha and beta particles: great for detecting surface contamination and measuring weakly active spec...
