X-radiation in early colour sets

[kalee20]

Originally Posted by Charles_

Einstein got his (first) Nobel prize for the photo-electric.
His genius was to realise that no matter how MUCH radiation was landing on a target it would N E V E R provoke electron emission from the target, unless the quantum energy of the radiation was high enough.

SO the same is true of masts and all EM radiation. If the energy of the quanta is below the value required to knock electrons out of the molecular orbitals that are the basis of our organic LIFE, they C A N N O T harm you, WHATEVER the intensity of the radiation. Trust me, I am a Quantum Mechanic

I'd agree with the facts here, but not the conclusion.

X-radiation (the subject of this thread) is generally accepted to be treated with caution, and there are several useful posts within the thread.

However, so-called non-ionision radiation CAN have chemical effects. Moving down in frequency, visible light and even IR radiation, although not breaking bonds, can create ions (photocells!) and directly stimulate chemical reactions (photography!) by affecting electrons in the orbitals of silver atoms. And no-one can argue that intense light can permanently damage eyes - a chemical effect - even though the energy of each quanta is less than that of X-rays. Light and IR radiation can easily cause latent effects which may only become apparent years later in different circumstances - think of developing an old film.

Move down further in frequency - people living under power-lines or working in 50Hz high-field strength environments report feeling unwell.

Move down to DC and experiments seem to show that animals navigate using the Earth's steady field, which must therefore be affecting their electrochemical nervous system.

The mechanisms are certainly more complex that simple ionisation, but while the potential to affect chemistry is there, the potential to cause harm is also there, whatever the frequency.

[space_charged]

Yes but to cause mutations, a base pair in the DNA must be changed or a pair added or deleted. Not the sort of thing that non ionising radiation is going to do. Lower frequencies can excite bond stretching and bending modes, sure, but not break a covalent bond. The effect is just that of heating. If there is enough of that, yes it can harm, just as anything other source of heat can burn you.

As to the eyes, there are special molecules that evolution has "deliberately" made sensitive to chemical change by specific frequencies of light. Yes, they could be damaged by excess light. That may be by heating effects really, which is just about all the lower frequencies can do as in bending and stretching modes. In fact the change
caused in light receptors is just our old friend cis/trans isomerisation. The energy of that transition is a long way below covalent bond breaking.

There are also proteins that incorporate iron in a form that reacts to magnetic fields, such as ferritin. These have been known for a long time. Again these molecules have been "designed" by the blind watchmaker to react to magnetic fields. There may well be other magnetic receptors too, but again they have evolved to detect magnetic fields.

As to the transmission line stuff, I don't think there is any creditable evidence of harm in the refereed journals. There is so much hearsay on this that I'll not go as far as I'd like to on this one.

Chas

[kalee20]

Originally Posted by Charles_

Yes but to cause mutations, a base pair in the DNA must be changed or a pair added or deleted. Not the sort of thing that non ionising radiation is going to do. Lower frequencies can excite bond stretching and bending modes, sure, but not break a covalent bond.

True, but lower frequencies can give rise to other reactions which then cause covalent bonds to be broken.

Visible light can't break a C-O bond, or an H-O bond. But in the presence of chlorophyll, these bonds ARE broken, oxygen is liberated, and glucose formed.

It's not inconceivable that a chain reaction mechanism exists such that low frequency radiation indirectly leads to DNA mutatution. I agree that it's far less likely than direct absorption of a high-energy photon breaking a chemical bond, probably by several orders of magnitude, as all elements in the chain must be present. My example of chlorophyll above is a rather exotic molecule, if you postulated the likelihood of a molecule of that formula being present in a cell you may rule it out as sounlikely as to not be worth considering yet the stuff does exist in vast quantities. And, DNA replication, if not mutation, at least is affected by light in plant cells.

Experiments and analysis are good for showing that something is possible, but a finite number of null results don't show that something is never possible, only that it didn't happen under the conditions of the trial.

Originally Posted by Charles_

I know a slightly soft EHT rectifier can conduct reversed biased by "cold cathode" emission... I constructed a voltage ladder of five stages... The result was an EHT of probably 50kV, estimated from the spark.

I applied that to an EHT rectifier valve but with the heater cold, so using cold cathode emission. I used a GM tube on a six foot window pole to probe for X-rays and the entire thing was inside a metal box, except for the opening which was pointing away from me.

The geiger went MENTAL when I got it near the aperature, but was OK where I was standing.

Now that's interesting! The pressure would have to be pretty low. But yes, under these conditions, there would be a high voltage across the valve. And with a bit of gas, yes there would be current flow. But there would have to be so few gas molecules that electrons liberated from the cathode (by ion bombardment?) stood a good chance of getting to the anode without colliding with a gas molecule on the way, and losing their energy. More gas would of course lead to avalanche breakdown and clobber the EHT sourcein any case.

This is a possible condition in a TV set (bringing back on topic!) after all - an open-circuit heater in the EHT rectifier, or the warming-up time. X rays could be produced by this valve, obviously in pulses at line frequency. So it's not just the shunt stabiliser valve to be wary of after all...

[BGmidsUK]

This is a very interesting thread, highlighting something I'd forgotten about and hadn't really considered a serious risk despite seeing warnings in various sets. Something to be very aware of when I get round to getting my Dynatron CTV7 in service, as I believe it uses the GY501+PD500 combination.


Brian

[Tazman1966]

No x-ray worries there Brian it uses at tripler

[BGmidsUK]

That's a relief it's ages since I've had the back off! Shows how bad my memory is sometimes.

I'll have to dig out my "Deccavison" 12" portable as I'm sure this also has an X-ray warning label inside!


Brian