Output tube radiation exposure - thoughts?

Honest1: I thnk it has more to do with the voltage the tubes operate at, rather than the frequencies they are amplifying. I don't think there is a problem until you start getting into much higher voltages than any audio amplifier uses, But at those voltages, tubes can emit Xrays. May be an issue with CRTs, not sure.

Lonestarsouth: This is utter nonsense!! Ionizing radiation only can occur when sub-atomic particles are excited by a high energy, high frequency power source. If your statement was true then electrostatic loudspeakers would have been ultra-deadly.

Actually, I believe that Honest1's statement about x-rays potentially being generated by high voltage tubes (much higher than any audio tube would use) is correct. As I understand it, an x-ray tube functions by bombarding the material in its plate with electrons that are emitted by a heated cathode, and then accelerated to high energy levels by means of a very high dc voltage applied to the plate. The voltage is typically in the range of 30,000 volts or more.

The analogy to electrostatic speakers is not applicable. While several thousand volts may be present between the elements of an esl, there is no electron emitter, no vacuum, and no plate being bombarded.

X-ray emission was definitely an issue with early tv sets, both from their crt's and from the tubes in their high voltage power supplies. Modern tv's and crt monitors use solid state power supplies, and presumably/supposedly limit x-ray emission from crt's via lead shielding which is impregnated into the glass.

See this wikipedia article for further information:

http://en.wikipedia.org/wiki/X-ray_tube

Regards,
-- Al

Well A1marg... what amplifies operate at 30 kVa? Not even the huge WAVAC amps run near that.

If the above were true then we all would have been dead a long time! Tubes are around quite a while - long enough to have wiped out the entire earths population.

We get more radio radiation from the thousands of satellites orbiting the earth - not to mention cell phones!

Enjoy your tube equipment gentlemen and ladies!

My advice: Don't eat yer tubes, and you'll be OK. This is good advice if you live in an old house with lead paint, as well.

Well A1marg... what amplifies operate at 30 kVa? Not even the huge WAVAC amps run near that.

Both Honest1 and I said very clearly and explicitly that the concern about X-rays would only arise in the case of tubes that operate at far higher voltages than are used in audio applications.

If the above were true then we all would have been dead a long time! Tubes are around quite a while - long enough to have wiped out the entire earths population.

I'm not totally certain as to what you are referring to by "if the above were true," but I assume it is my reference to early tv sets having an issue with X-ray emissions.

For starters, please read the last section in the Wikipedia writeup I linked to in my previous post, which is entitled "Hazards of x-ray production from vacuum tubes." Then please do some Googling on the subject and you will find additional commentary to the same effect.

I am an antique radio collector, and as such I have had occasion to accumulate significant knowledge about early tv sets as well (ca. 1946 to the 1960's). The issue was not that they would "wipe out the earth's population." The problem was that those sets, when viewed from close distances (such as children are often known to do), for considerable amounts of accumulated time, would pose unacceptable long-term health risks. As I said, those risks have presumably been eliminated in more modern sets.

Regards,
-- Al

This is a reply from an electronics engineer:

"Potentially hazardous radiation (e.g. X-rays): There are weak X-rays requiring about 1kV to 20kV to be generated, then medium X-rays needing about 20kV to 60kV, then hard X-rays needing 100kV to 1MV. The first group can theoretically come from tvs and oscilloscopes - they 'penetrate' about 0,1mm through glass to about 0,001 mm through metal - different depths for different metals. The other groups are irrelevant for this discussion.

So no fear - unless you go to sleep with a giant oscilloscope close to your ..... in which case you are so
queer anyway that radiation is the least of your worries.

Folks live close to 30kV - 100kV lines. Radiation cannot be caused unless there is a heated cathode, and an anode, contained in a special vacuum tube. But ozone can be smelled then.

Ozone to higher than one in a million concentration is considered potentially hazardous, but it is smelled long before that (hazardous as in affecting the respiratory system primarily; it can also cause a headache in some people). Such concentrations are very rare; it must be generated to get there. It is a powerful oxidant which in low quantities can be beneficial and is used as a purifier more potent than chlorine. Notably, a small quantity can be generated in air conditioners to purify the air. "

I would rather not begin to argue with him. He is a true scientist that knows his electrons.