After reading the pdf I was a bit disappointed about the lack of scientific content. In the text the only reference to another publication is to a book of the author himself.
Furthermore, where are the statistics that there is actually a problem that needs solving?
If, over several decades some gas has found its way into the internals of a valve, that gas can only be air: 20% oxigen, 79% nitrogen and 1% argon. A barium getter will quickly react with the oxigen, but it does nothing with the other gasses. So, if the problem is gas coming from outside, even 'reactivating' the barium getter still leaves 80% of the problem. Big deal.
In his own collection of two types of small signal valves he found improvement after baking the problem valves. What would have happened to those if they would just have been used in a real circuit? Is cathode poisoning in these cases a likely danger? Give me numbers: what percentage of valves die because of this? How much shorter valve life? Differences between small signal, power and transmitting types?
I'm not saying that the problem the author describes is not real, because I do not know. All I know is that I just plug in old valves and most of them just work perfectly.
Furthermore, where are the statistics that there is actually a problem that needs solving?
If, over several decades some gas has found its way into the internals of a valve, that gas can only be air: 20% oxigen, 79% nitrogen and 1% argon. A barium getter will quickly react with the oxigen, but it does nothing with the other gasses. So, if the problem is gas coming from outside, even 'reactivating' the barium getter still leaves 80% of the problem. Big deal.
In his own collection of two types of small signal valves he found improvement after baking the problem valves. What would have happened to those if they would just have been used in a real circuit? Is cathode poisoning in these cases a likely danger? Give me numbers: what percentage of valves die because of this? How much shorter valve life? Differences between small signal, power and transmitting types?
I'm not saying that the problem the author describes is not real, because I do not know. All I know is that I just plug in old valves and most of them just work perfectly.
Valves can last a very long time.
A TV and Radio engineer gave me a 1940's valve amplifier from a radio for my electric guitar. It blew a couple of capacitors on power up but after replacing the capacitors the valves burst into life and sounded very good.
I suspect air entering valves is a rare problem and not worth worrying about.
If someone is mistreating valves like banging them around then they deserve any problems they get.
A TV and Radio engineer gave me a 1940's valve amplifier from a radio for my electric guitar. It blew a couple of capacitors on power up but after replacing the capacitors the valves burst into life and sounded very good.
I suspect air entering valves is a rare problem and not worth worrying about.
If someone is mistreating valves like banging them around then they deserve any problems they get.
Wonderful English accent in these videos, easy to follow, Thanks for posting.
This Japanese 300B factory is a Hospital grade clean:
EMS???EMS?????????????????????????????
I was though these powerful induction heater could be the source from some damage in modern 300B tubes, but seems not true.
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After reading the pdf I was a bit disappointed about the lack of scientific content.
Ditto here, mainly for this be a famous author, he just related his test on the kitchen.
I conclude baking tubes are suited only to full glass DHT tubes without baquelite base.
Senile big ham radio tubes also not benefit from baking, as they can be heated in the RF amp without the HV for days.
I suspect these usual dust barium getter used on the tube glass had more some chemical elements than just barium.
Is cathode poisoning in these cases a likely danger?
It is a danger to ruin the tube, it is a subject that needs much more study, Iam sure the tubes factories know alot about it.
They just dont say it to us.
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Very cool! Thanks for posting the Mullard videos, wicked1. They sure had lots of gloppata machines going back then!
I especially liked the draftsman working in suit and tie
Very old-school, indeed!The inductive-heating process is shown at about 22:45 in the "Manufacture" video (the shorter one). I suppose heating the internal elements red-hot during evacuation of the tube would also bake-off any impurities or finger-oils left on the parts during handling. They didn't seem to wash any of the parts after assembly and before insertion into the tubes - and the workers were certainly handling the innards with bare fingers, even in the Mullard factory back in the good-old-days...
And they most certainly were not working in anything resembling a clean-room! All those gloppata machines need oiling, the high factory ceilings with "winged-residents", the open windows back in the days when roads may or (more likely) may not have been paved.
A testament to the ruggedness of tubes, indeed!
Just try processing a wafer of silicon under THOSE conditions!!
Again - seriously - are we really concerned about somehow baking the getter in older tubes after watching some of these videos? Life is short, there's lots of amps to build and beaches to go explore.
Perspective, people, perspective.
~ RF Dude
As precisely the same problem appears to be solved by the getter during manufacture, I assume the getter can mop up nitrogen OK. Metals do form nitrides! Argon maybe not.Parafeed813 said:
I suspect that touching most metal parts does not matter too much. Occasionally a partial fingerprint can be seen on an anode. The cathode surface is different; that should never be touched.rfengineer2013 said:
"And they most certainly were not working in anything resembling a clean-room! All those gloppata machines need oiling, the high factory ceilings with "winged-residents", the open windows back in the days when roads may or (more likely) may not have been paved".
Unpaved roads in the UK in the 50's? What part of Fairyland are you from?
Unpaved roads in the UK in the 50's? What part of Fairyland are you from?
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Other than the demonstrations, I thought they used tools all the time (rather than fingers), on the inner pieces.. Pliers, etc. Then they even mention the "new" production line is automatic "and you'll notice they are not touched by a human hand" or something the announcer says.
and the "clean room" I mention was at a couple of particular phases in the manufacture parts are assembeled behind glass in a separate room, away from the main assembly line.
But yeah, quite industrial!
and the "clean room" I mention was at a couple of particular phases in the manufacture parts are assembeled behind glass in a separate room, away from the main assembly line.
But yeah, quite industrial!
Occasionally a partial fingerprint can be seen on an anode.
I bake two Ulianov 6C33, on the next day appear inside of the tube glass base(next to the pins) a very white partial fingerprint.
So in the 1983 Ulianov factory they dont used gloves.
I will post a complete report as the getter tubes are changing yet.
As a side-note, a person will discover very quickly that this circuit is oscillating if he (or she) gets metal jewelry anywhere near it.
The induction field will heat metal pieces placed inside the coil but a wedding ring, for instance, is a one-turn transformer loop that will pick up the RF energy radiated from the induction loop, and it will become uncomfortably hot very quickly if the persons hand (wearing a ring) is anywhere near the energized induction coil.
Another reason to not only keep one hand in the back pocket when working around equipment, but also to keep the correct hand in the back pocket! (or, better yet, remove any metal jewelry before working on any high power equipment)
One of the joys of working with RF
~ RF Dude
Please don't tell me they had moved past thatch and wattle construction by then, too!
I purchased a bargain used "Wood Welder" several years ago with the idea of the instant gluing of wood joints by RF in my basement workshop.
Not a good idea, it buggered up the TV reception completely and the arcing was quite spectacular.
The 4 big old power tubes have some value apparently to amplifier builders.
RF induction heaters should and must be operated inside a grounded Faraday cage. Period.
Unless the induction heater itself has its own shielding - in which case it is a commercial unit or you already know how to do all this and are not reading this post.
Model 4000 Welder On the Wood Welder the tuned antenna is built into the hand unit.
When I contacted the manufacturer about interference, thinking my used unit had a problem, they said, "that is what they will do".
Workrite has been making these RF welders, basically unchanged since the 30's.
I was referring mostly to any would-be gung ho DIYers...
The Workrite unit needs to be grounded, and it would be a very good idea to run it in a grounded metal building too... I didn't look up that unit to see what power and frequency it runs, but there are restrictions on radiated power and frequency in the USA.
The Workrite unit needs to be grounded, and it would be a very good idea to run it in a grounded metal building too... I didn't look up that unit to see what power and frequency it runs, but there are restrictions on radiated power and frequency in the USA.
the problem is that these seem to be free running oscillators, meaning that their frequency will be shifting with load, as will their harmonics.
The Workrite 4000 appears to use 810 tubes, so assuming a pair, that's a solid 1kW output. A quick look showed commercial production units using large air cooled ceramic transmitting tubes.
Haven't found their freq assignment yet...
The big problem is out of band spurious emmissions.
Also there can be arcing... (apparently when it isn't used properly).
But these are not the same as the RF induction heaters used to fire off tubes. Similar in some respects, but not the same.
_-_-
The Workrite 4000 appears to use 810 tubes, so assuming a pair, that's a solid 1kW output. A quick look showed commercial production units using large air cooled ceramic transmitting tubes.
Haven't found their freq assignment yet...
The big problem is out of band spurious emmissions.
Also there can be arcing... (apparently when it isn't used properly).
But these are not the same as the RF induction heaters used to fire off tubes. Similar in some respects, but not the same.
_-_-
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