Radioactive Meters?

Concerned about the panel meters in your old radio gear or older military surplus electronics or radio equipment?

While there is no substitute for testing, the color of the glow (in a darkened room) or the color of the paint itself may indicate the posibility that the meter was made with radioactive materials or paint. Usually this stuff is applied to the indicating hands or needle and on markings on the dial.

Any dial that keeps glowing for days without external stimulation is suspect of being radioactive (duh!).

1. White- non-phosphorescent,designed for flood lighting in vehicles or aircraft

2. Green(ish) phosphorescent, needs UV stimulation to glow is not radioactive. This was used in earlier WWII aircraft and Link trainers with flourescent black lights. A similar paint, slightly more yellowish, like common "glow-in-the-dark paint" was used on later military radio knobs and also requires external UV lighting or "charging up" with room light in order to glow.

3. yellowish to brownish- could be self-luminescent, radium or other alpha emitting isotope mixed with a phosphor (best checked with a scintillation counter that is capable of detecting alpha emission. Alpha particles can be blocked with paper, so most geiger counters are rather insensitive to them. This paint is dangerous if ingested, but I believe it was discontinued by around 1944. Although the instrument's phosphor paint may have decomposed and no longer glow, the radium is probably as good as ever. This paint should not be confused with plain yellowed paint that is often seen on aircraft istruments that have sat in the sun for years.

4. Sealed tritium (hydrogen-3) ampules with a phosphor coating on the inside of the ampule- This is used in newer compasses etc, and is much safer than the radium paint, because the tritium gas is sealed in the ampule, and even if broken, it disperses rapidly, leaving no radioactivity behind. Nearly all military stuff uses the green-ish phosphor, but other colors are possible.

5. deep violet color. Presently not identified, rarely seen, but seems to need no external UV to goow by itself. Presumed radioactive. Can be found on some older GRC-106 and R-390 radios.

Probably the most potentially dangerous sustance is the adioactive paint applied externally to knobs and engraved legends on early WWII radios, it tends to flake off, and if ingested, is quite capable of lodging in the lung and starting a little tumor party.

The same or similar stuff might be inside the meters. As long as the meter glass is not broken, and the meter is not disassembled, they are safe enough. Just don't sleep with a case of them under your bed!