So I noticed my output tubes sounded better in the shade, and when sun shone on the plates, the tone suffered.
Has anyone got any ideas on UV protection, (while maintaining the beautiful appearance of the output tube)
😉
Has anyone got any ideas on UV protection, (while maintaining the beautiful appearance of the output tube)
😉
Contact a company that makes glass filters for photography. Example, a 52mm UV filter for your camera lens. Look through that UV filter, you will barely see the effect, but it does attenuate UV.
See if they will apply the UV coating to the glass on your output tubes.
Most windows filter out some of the UV, but do not filter out lots of IR heat.
Have UV coating applied to your windows.
Are you certain that the suns UV is affecting only the output tubes, perhaps it affects the input and driver tubes too.
Shielding them, one by one, is the only way to tell which tubes are effected.
Is it possible the sunlight is very bright, and that it is adding additional heat to your tube plates?
See if they will apply the UV coating to the glass on your output tubes.
Most windows filter out some of the UV, but do not filter out lots of IR heat.
Have UV coating applied to your windows.
Are you certain that the suns UV is affecting only the output tubes, perhaps it affects the input and driver tubes too.
Shielding them, one by one, is the only way to tell which tubes are effected.
Is it possible the sunlight is very bright, and that it is adding additional heat to your tube plates?
Thanks 6A3. Could be the extra heat. Or some electron-chemical UV thing...wife happily suggested sunscreen
Its not a major , may see how it goes or just live with it
Its not a major , may see how it goes or just live with it
The Earth is closest to the Sun during the first week of January. Even in NZ. So an umbrella might help.
Due to precession of the Earth's axis the North Pole will point a long way from Polaris in about 2000 yrs.
But back to Polaris again in about 25000 yrs. If there is anyone or anything that cares by then.
The weather here tonight makes that hard to believe, it looks like 6-8 inches more snow.
I'll be spending some time on the tractor in the morning, iNet here is on a dish, that will quit tonite for sure.😀
Due to precession of the Earth's axis the North Pole will point a long way from Polaris in about 2000 yrs.
But back to Polaris again in about 25000 yrs. If there is anyone or anything that cares by then.
The weather here tonight makes that hard to believe, it looks like 6-8 inches more snow.
I'll be spending some time on the tractor in the morning, iNet here is on a dish, that will quit tonite for sure.😀
Very much doubt plates are affected in any way.
Rugged beasts, designed to survive becoming red hot, a huge and continuous electron shower, accelerated by hundreds of volts, not receiving but emitting X-rays ... they will not even notice s few UV photons.
Temperature rise can only be a few degrees.
Not too sure something is actually happening, but IF do, I'd rather expect some photo effect on traces of gas remaining inside tubes vacuum.
Practical experience: sometimes found neon inside NE2 bulbs not lighting if fully in the dark, but "triggering" if subject to ambient light.
In the old days, neon bulbs were much used: power indicators, SCR/TRIAC triggers in phase control circuits and as Audio modulators in Tremolo circuits driving an LDR.
Here they are wrapped in black electrical tape, it was maddening to have tremolo circuits not working when inside amp cabinet, starting happily when on bench ... WTF?
When I was working on HF transceivers I used to tape a neon bulb to the outside of the coax going to the dummy load. If it was transmitting the bulb would light (telling me it was unsafe to play with the coax connection).
In a book I once read about cold-cathode glow discharge tubes (G. F. Weston, Cold cathode glow discharge tubes), the author claimed that that is due to photoelectric effect on the electrode that is used as the cathode. The wavelengths that help a glow discharge tube to start up depend on the work function of the cathode, although traces of sodium in the glass could also have some effect.
I think the idea was that photoelectric effect would let some electrons escape from the cold cathode. When the electric field is strong enough, they will ionize some neon atoms and once that is done, you get a chain reaction and the glow discharge will build up. If a cold-cathode glow discharge tube has to start up quickly in the dark, you either need a radioactive primer that always keeps some part of the gas ionized or an extra electrode that always keeps a small glow discharge running.
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Me too......(that´s a new one ? Morgan Jones ? case for suntan blocker Number 30 ??). .😎
I live in an area with relatively high ground radioactivity ~ 5000uV sieverts/yr and my tubes sound wonderful; way above UV sunscreen exposure worries. Note; in the 1960´s cold war, Russian aircraft used tubes to avoid being affected by any em pulse, plus all the cosmic radiation exposures that didn´t effect their operation.
Listen easy.
I live in an area with relatively high ground radioactivity ~ 5000uV sieverts/yr and my tubes sound wonderful; way above UV sunscreen exposure worries. Note; in the 1960´s cold war, Russian aircraft used tubes to avoid being affected by any em pulse, plus all the cosmic radiation exposures that didn´t effect their operation.
Listen easy.
I guess photoelectric effect has very little impact on the cathode of a normal valve, as it emits electrons anyway by thermionic emission. Maybe it has some impact on the control grid leakage current?
Glass is an effective UV blocker.
So at least that is ruled out.
It could be related to visible or IR part of spectrum.
Please share tube types and maker details.
So at least that is ruled out.
It could be related to visible or IR part of spectrum.
Please share tube types and maker details.
Nickel plates will photo-emit electrons from 5eV and up, which is in the UVC band and blocked by glass anyway.
Barium in the getter however emits from 2.48eV and will emit from visible green/blue light - so this might be light falling on the inside of the getter patch causing stray electrons, but they probably would just form a cloud around the getter as its isolated and would become +vely charged...
Barium in the getter however emits from 2.48eV and will emit from visible green/blue light - so this might be light falling on the inside of the getter patch causing stray electrons, but they probably would just form a cloud around the getter as its isolated and would become +vely charged...
I very much doubt that, a black object in a vaccum in a glass bottle may heat up many tens of degrees C in direct sunlight, just like the inside of a car or greenhouse, especially as there's no atmosphere to cool it.
Cars have closed windows, and the tubes have a small area...but it just could be the reason, easily checked with a pointing type thermometer, the hand held type used to check furnace temperature.
It is not vacuum, TV tubes were vacuum, much thicker walls than tubes, here same principle of sacrificial gas as incandescent bulbs is encountered.
It is not vacuum, TV tubes were vacuum, much thicker walls than tubes, here same principle of sacrificial gas as incandescent bulbs is encountered.