hello. i found a pdr-43 radiac meter at my local ham radio swapmeet today. the device looks like this: http://www.civildefensemuseum.com/southrad/im125dpdr43.html as a just for fun project, i would like to attempt to make it functional. right now the unit powers on but adjusting the check meter between beta and gamma does not do anything and the roentgen meter reads a 500roentgen/hr immediately upon powering up. i dont know much of anything about radiation or radiation detection but i am a ham radio operating and am fairly comfortable with electronics design. any help or resources would be great.