OK, I thanks your detailed explanation and all others posts.
If I test something I will report.
Best Regards
I've always liked the last 2 videos, and this is a good place to post them, in case someone isn't completely aware of what an induction heater does. The first video is someone's diy induction heater.
DIY induction heater - YouTube
??-29 in the induction heater- melting glass - YouTube (This guy really does not like the gu-29)
induction heater levitation melting aluminum - YouTube
DIY induction heater - YouTube
??-29 in the induction heater- melting glass - YouTube (This guy really does not like the gu-29)
induction heater levitation melting aluminum - YouTube
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If you really want to see what RF Induction heaters look like (8th page) and what they do for vacuum tubes, then click this link. It is a write up of a tour of a Chinese vacuum tube factory.
http://www.diyhifisupply.com/files/diyhs-tj-factory-tour.pdf
That is what tube induction heaters look like.
And by the way, I whole-heartedly do NOT endorse the website that this .pdf is linked to. I went there awhile ago to purchase two tube amplifiers and two pre-amps (I was in Hong Kong going on 5 days worth of business) and had nothing to carry back. So I thought that I would grab a nice tube pre-amp and amp (named after Ella) for myself and another matching set for my friend who had ponied up the money. I had no luggage, lots of pounds allowance, and why not? (I was still single at the time) They were very centrally located in near Kowloon's TST district at the time and I had time between appointments to go up to their showroom.
Well, I went to the office/showroom, the girl there was nice as I looked around. However, I had a few questions like could the chassis be packed carefully, massive toroidal transformers possibly be removed, and some parts disassembled, if I could audition the floor model, and could I be cut a discount for some spare tubes. The white haired guy there sized me up, looked at me if I were from another planet, and said, "The amp is very good, why do you want to audition it?" Turned and walked away before I could answer to his face.
I said, "Wow, thanks." and I walked out.
I came back, gave my friend his money back, told him to keep his eyes open for a Marantz 8b instead (12 years ago, they were still relatively affordable ad nice sounding).
http://www.diyhifisupply.com/files/diyhs-tj-factory-tour.pdf
That is what tube induction heaters look like.
And by the way, I whole-heartedly do NOT endorse the website that this .pdf is linked to. I went there awhile ago to purchase two tube amplifiers and two pre-amps (I was in Hong Kong going on 5 days worth of business) and had nothing to carry back. So I thought that I would grab a nice tube pre-amp and amp (named after Ella) for myself and another matching set for my friend who had ponied up the money. I had no luggage, lots of pounds allowance, and why not? (I was still single at the time) They were very centrally located in near Kowloon's TST district at the time and I had time between appointments to go up to their showroom.
Well, I went to the office/showroom, the girl there was nice as I looked around. However, I had a few questions like could the chassis be packed carefully, massive toroidal transformers possibly be removed, and some parts disassembled, if I could audition the floor model, and could I be cut a discount for some spare tubes. The white haired guy there sized me up, looked at me if I were from another planet, and said, "The amp is very good, why do you want to audition it?" Turned and walked away before I could answer to his face.
I said, "Wow, thanks." and I walked out.
I came back, gave my friend his money back, told him to keep his eyes open for a Marantz 8b instead (12 years ago, they were still relatively affordable ad nice sounding).
This one is good.
At 4:26 you can watch them flash the getter
How It's Made - vacuum tubes - YouTube
At 4:26 you can watch them flash the getter
How It's Made - vacuum tubes - YouTube
This induction heater you mention as many others used in the tubes factory are suited only to activate the getter in the first time.
I can not use this kind of device again, the getter already is adhered on the glass tube.
My tubes are from 1970s and 80, after 30 years on the shelf some air may entered on the tube or oxide cathode dust loose inside, so I need a safe way to heat the getter on the glass surface to clean this impurities;
I will think something.
You can not get the air back out, unless there is some unflashed getter material or material that can still grab some molecules, there is nothing much you can do. The tubes are likely just fine, why do you think otherwise? If they are typical 6L6 or 6CA7/EL34 type tubes, just run the fils and fire them up.
There are some concerns with large size transmitting tubes.
Not many with typical hifi tubes...
You can use an induction heater to *heat* the inside metal parts of the tube, regardless of what has happened with the getter... the only question is unequal heating on the envelope if the getter looks conductive to the RF induction current.
There are some concerns with large size transmitting tubes.
Not many with typical hifi tubes...
You can use an induction heater to *heat* the inside metal parts of the tube, regardless of what has happened with the getter... the only question is unequal heating on the envelope if the getter looks conductive to the RF induction current.
They are all Triodes= 6n1P, 6N6P, 6C33 and GM70.
I will decline to heat the internal metal parts for not activate the cathode and avoid cathode poison.
Seems to me the getter on the glass will chemical absorb/transform the air inside if it could be heat to a working temperature.
I will decline to heat the internal metal parts for not activate the cathode and avoid cathode poison.
Seems to me the getter on the glass will chemical absorb/transform the air inside if it could be heat to a working temperature.
I would be hesitant to re-flash a getter using an induction heater. I expect uneven heating of the getter flash on the glass would crack it.
Heat it in an oven.
Heat it in an oven.
I had one senile 6C33 from 1983 I would sacrifice to this oven test.
But What I must look on the tube after the bake??
(anything less using it in the amp)
But What I must look on the tube after the bake??
(anything less using it in the amp)
The getter is heated up with an induction heater to many times that of an oven.
So its unlikely the oven would make much difference.
So its unlikely the oven would make much difference.
It's amazing that the only times in the video where you see the workers wearing gloves are when the tube is HOT or during final packaging into the "gift box" set... (to avoid getting lunch schmutz on the pretty box, I guess 🙂 )
I was especially horrified to see the worker handling the cathode with bare fingers!
OTOH, I suppose handling tube parts isn't as critical as handling a wafer of silicon, where clean-rooms come in all varieties of extreme clean-ness.
So, does some of this video put this "gettering" discussion in perspective? It really should, IMHO.
~ RF Dude
That would be nice if it were so, but it isn't. (Not so) vacuum tubes have about a billion ionizations every second that cause unwanted grid currents and flash-overs, plate current run-aways, and extra noise. There is a lot of left over gas in there, and barium getters do absolutely nothing about removing chemically inert gases that are always present in the atmosphere.
Also, using an induction heater to heat up the plate is a really bad idea. This is likely to make the problem worse, not better. Like red plate operation, it's likely to liberate trapped gas, not remove it.
Could this be why modern valves don't last very long? The cathode surface should certainly not be touched by bare fingers.rfengineer2013 said:
The EML workers made a special effort to the camera, when the camera is gone the situation get worse.
This tube factory is one of the best today and its site is pretty informative in useful info, how would be a chinese factory so...
Hi,
I have a few GEC KT-88's that have been on a shelf in my basement for almost 30 years. Recently I tested them and they were all "good".
If I left them on the tester with just the heater on for a period of time, would they test any better?
Thanks, Terry
I have a few GEC KT-88's that have been on a shelf in my basement for almost 30 years. Recently I tested them and they were all "good".
If I left them on the tester with just the heater on for a period of time, would they test any better?
Thanks, Terry
There is a lot of left over gas in there, and barium getters do absolutely nothing about removing chemically inert gases that are always present in the atmosphere.
This is a impressive assertion, do you had a impressive proof of this getter inefficiency??
When induction heaters began to be used in valves industry??
Could be for the use of induction heater the current 1998 WE 300B had a lower sound quality than the old NOS WE 300B??
It would be good to these tubes in sone way, since does not happen cathode poisoning.
Senile rare tubes are usually sold as ''strong'' on Ebay at varying prices.
If one was concerned about improving the getter efficiency when turning on a valve for the first time for a while, and didn't want to go the oven bake path, then adding a layer of insulation on the glass where the getter is would assist raising the getter material temperature - perhaps in a better way than trying to crank up the plate dissipation to achieve the same rise in getter temperature. The issue is all about heat flow and effective 'thermal resistance' from the central structure to the getter material, and from there to ambient. Obviously the aim is not to raise the temperature of the glass to too high a level, but the getter is normally not placed where max glass temperature occurs from anode radiation.
after watching that, some Mullard Blackburn video's from the 50's or 60's showed up, and they were incredible!! They NEVER touched anything in those factories. Some steps were performed in cleaner rooms (not clean rooms by todays standards)
They do use induction heating to heat all the metal during vacuuming the gas out, and then again later to flash the getter. so they were using them back in the 50's, that for sure.FullRangeMan;3398354} When induction heaters began to be used in valves industry[B said:
http://www.youtube.com/watch?v=GDvF89Bh27Y
http://www.youtube.com/watch?v=dErsA6wFmlM
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