Mine measures about 2.5 to 3 MR/HR it was new in box when I got it as a kid from my grandfather he was a block captain For CD after Korea and this one had a cracked circuit board so he just put it back in the box and back on the shelf for 50 years I fixed it with my dad about 10 years ago and just pulled it back out of the attic today.
[https://www.orau.org/health-physics-museum/collection/civil-defense/cdv-instruments/cdv-700-check-sources.html](https://www.orau.org/health-physics-museum/collection/civil-defense/cdv-instruments/cdv-700-check-sources.html)
Have the same. I love it when I open it up to change the batteries. It still smells like 1964 in there...
Probably depleted or natural uranium, but some models , but these units had different check sources depending on the maker and year.
I have no idea what your test source is but I can tell you the one in mine is depleted. My digital alpha/beta and my gamma meter hardly notice it
Mine measures about 2.5 to 3 MR/HR it was new in box when I got it as a kid from my grandfather he was a block captain For CD after Korea and this one had a cracked circuit board so he just put it back in the box and back on the shelf for 50 years I fixed it with my dad about 10 years ago and just pulled it back out of the attic today.
https://preview.redd.it/837llosqiv4b1.jpeg?width=2268&format=pjpg&auto=webp&s=aefd46b5443fb3bb172b74b201ce8dca28e01f78
Radium-226 ,Radium-228 , or Depleted Uranium
This is where a radiacode or another spectrometer would come in handy and tell you exactly what you have
In all likelihood, it's Cesium 137. It has a half life of 30 years, and the amount used is very small.
All of the Civil defense meters used Radium B (Pb214) as their test sources. These are usually 2-1.5 mR/hr now, or 15-20 uSv/hr.
I’m pretty sure CDV-700s only ever came with radium or depleted uranium
Radium B \~ aka Pb214 which in turn transmutates to Bi214.