A BIG box full since the stated maximum dissipation is 1.7 mW per plate. It is a dual triode. The "plate current" spec in the data sheet is 13uA. It's not stated if that is the maximum or the typical operating current. The plate voltage is specified as 80 volts MAX, but the plate curves go out to 200 volts. Positive grid bias is needed at 'low" plate voltages. It is a planar triode, since it is offspring of a Vacuum Fluorescent Display device.
I consider the Nutube to be two things:
It gets used due to a "Neatness" or "Cute" factor.
A nice lesson in engineering of how to use a tube for an application, no matter the difficulty of making it work acceptibly well.
Just my opinions.
It gets used due to a "Neatness" or "Cute" factor.
A nice lesson in engineering of how to use a tube for an application, no matter the difficulty of making it work acceptibly well.
Just my opinions.
To make a active device smaller you need a way to cool it efficiently, one of the better ways to cool tubes is evaporative steam cooling meaning that you let water boil away at anode, cool the steam and return the water to the anode again. As the enthalpy of vaporization for water is very high, 2260KJ/Kg is it possible to get very efficient cooling with a limited quantity of water and at the same time the temperature is kept constant at 100C.
Look here
for an example, a tube that give 100kW output power up to 30MHz and still is not bigger than 420mm long and 165mm in diameter, (there are even larger ones with 250kW dissipation).
Are there any comparable solid state alternatives available now that are smaller?
Look here
Are there any comparable solid state alternatives available now that are smaller?
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The NuTube was developed by Korg and Noritake. Korg makes electronic musical instruments and Noritake makes VFD's and other glass products. The overall sales volume for VFD's has been declining since the 90's as other lower cost devices have emerged. The NuTube is a reworked VFD, and a neat way to make a few new Korg products and keep an old VFD line going.
I got on the mailing list when the NuTube was announced and that's how I got the pre production data sheets. I never found any small quantities of the NuTube for less than $50, so I have never tested one.
I got some surplus VFD automobile clock boards for $3 each, ripped the displays off and tried to use them as triode amplifiers. They do work (sort of) but the Gm is even lower than the NuTube, as is the Mu. They are not as linear as the NuTube either, so some development activities were involved in making the NuTube work as good as they do.
Most of the commercial applications I have seen for the NuTube involve musical instruments or effects boxes, but at least one diyAudio forum builder is making hybrid amplifiers with them.
I have seen some success using "pencil" tubes like the 6418, 6088, and 5678 in music synthesizer and guitar preamp applications at voltage levels as low as 12 volts. The sweet spot seems to be around 30 to 50 volts with the higher current tubes though. THD for a line level signal output is in the 1% range, but microphonics is the biggest issue, especially with the 6418. Both of my sources for these tubes are no longer available, so all of that work is now in a box on the shelf.
You should see the valves used in RADAR installations!! They are quite large and are often liquid cooled. But when the power ranges from 7 kW to 20 MW ....
Keeping the water at 100 degrees C, requires a very well closed system.
So does 600 degree F steam for a WWII era US Naval Destroyer.
In electronics, the rule is keep the smoke from coming out.
In coolers and boilers, the rule is keep the steam from coming out.
I have heard, true or not, that a transmitter at the DEW line uses a walk-in tube. It has to be cleaned periodically.
I talked to a technician at one of the 8VSB digital TV transmitters. He had four Klystron tubes, 60kW each one, that is 240kW.
There was only 238kW coming out of the combiner. The combiner effectively was a 2kW space heater.
So does 600 degree F steam for a WWII era US Naval Destroyer.
In electronics, the rule is keep the smoke from coming out.
In coolers and boilers, the rule is keep the steam from coming out.
I have heard, true or not, that a transmitter at the DEW line uses a walk-in tube. It has to be cleaned periodically.
I talked to a technician at one of the 8VSB digital TV transmitters. He had four Klystron tubes, 60kW each one, that is 240kW.
There was only 238kW coming out of the combiner. The combiner effectively was a 2kW space heater.
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Well, saturated steam at 100 celsius degrees is very easy to be managed (every car's radiator does better), whilst at 600 fahrenheit (around 315 celsius) requires around 100 bars.
This document is interesting as an introduction on how to design heat exchangers with boiling liquids:
https://www.researchgate.net/profil...at-Transfer-with-Boiling-and-Condensation.pdf
This document is interesting as an introduction on how to design heat exchangers with boiling liquids:
https://www.researchgate.net/profil...at-Transfer-with-Boiling-and-Condensation.pdf
Many TV transmitters today use a tube of relatively new design, the IOT, Inductive Output Tube. They are smaller, more efficient than a Klystron, and can be operated linearly over a wider bandwidth. DTV requires constant gain over 6 MHz of bandwidth.
Tubelab_com,
Thanks for the reminder!
I could not remember the name, IOT, Inductive Output Tube.
The IOT is loosely a derivative of the Klystron from the 30s or 40s.
And then there were Traveling Wave Tubes (TWT), but that is another story.
Let's see, an antenna, a delay line, a TWT, and another antenna, is that useful?
The US has rewarded the lesser of two methods to be the choice for broadcast standards.
The FM Stereo technique that was picked decades ago was pretty good, but the technique that did not win out was superior.
The US TV digital standard, 8VSB, is not nearly as good for multi path interference as OFDM.
It seems like cities might not have been important when making that decision.
Politics at work!
Thanks for the reminder!
I could not remember the name, IOT, Inductive Output Tube.
The IOT is loosely a derivative of the Klystron from the 30s or 40s.
And then there were Traveling Wave Tubes (TWT), but that is another story.
Let's see, an antenna, a delay line, a TWT, and another antenna, is that useful?
The US has rewarded the lesser of two methods to be the choice for broadcast standards.
The FM Stereo technique that was picked decades ago was pretty good, but the technique that did not win out was superior.
The US TV digital standard, 8VSB, is not nearly as good for multi path interference as OFDM.
It seems like cities might not have been important when making that decision.
Politics at work!
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The FM stereo multiplex technique is a disaster for the signal to noise ratio during weak reception, but they had to come up with something that was backwards compatible with FM mono receivers and channel allocations. But that's off topic, of course.
Gyrotrons manage some fairly impressive power density, especially when we consider their frequency range. Active development on tubes continues- where there's a market. There is a market for klystrons, TWTs, IOTs and gyrotrons. As the race for fusion power intensifies, the market for gyrotrons may further increase.
The market for a nuvistor in a TO-92 package on the other hand, doesn't really exist. A few might find their way into esoteric mic preamps (if they were low enough noise) or effects pedals, but that's about it.
I think you'll find that the concept of the triode may come back in a very miniaturized form (who knows when), but it'll just be a different way to do a microprocessor.
Same way you may see new steam locomotives at some point (depending upon the direction fossil fuels take and the miniaturization of nuclear technology)- but they won't look anything like the steam locomotives of the 1950s.
Old technologies do get revisited, but they usually take a rather different form.
The market for a nuvistor in a TO-92 package on the other hand, doesn't really exist. A few might find their way into esoteric mic preamps (if they were low enough noise) or effects pedals, but that's about it.
I think you'll find that the concept of the triode may come back in a very miniaturized form (who knows when), but it'll just be a different way to do a microprocessor.
Same way you may see new steam locomotives at some point (depending upon the direction fossil fuels take and the miniaturization of nuclear technology)- but they won't look anything like the steam locomotives of the 1950s.
Old technologies do get revisited, but they usually take a rather different form.
This thread sparked up another old memory that had been stuck in a dark corner of my brain since the mid 1970's.
One of my early tasks in my 10 years in the cal lab at Motorola was to change a BWO tube in a spectrum analyzer. This beast of a tube was the size of a large lunch box and was too heavy for the older techs to change. Most of that weight was in the magnet structure, and later model analyzers and sweep generators used a tube with an external magnet that was far easier to change.
The BWO tube is a "Backward Wave Oscillator." It is an evolutionary branch from the TWT "travelling wave tube" family whose main claim was that it could be tuned across a very wide frequency range by varying the helix voltage. The old HP sweeper we had could tune something like 8 to 12 GHz and could be swept across this entire range. Just the ticket for radar jammers.....just a bit to heavy to put in your car. The HP686C sweeper weighs in at over 100 pounds. The large rack mounted spectrum analyzer was far heavier.
One of my early tasks in my 10 years in the cal lab at Motorola was to change a BWO tube in a spectrum analyzer. This beast of a tube was the size of a large lunch box and was too heavy for the older techs to change. Most of that weight was in the magnet structure, and later model analyzers and sweep generators used a tube with an external magnet that was far easier to change.
The BWO tube is a "Backward Wave Oscillator." It is an evolutionary branch from the TWT "travelling wave tube" family whose main claim was that it could be tuned across a very wide frequency range by varying the helix voltage. The old HP sweeper we had could tune something like 8 to 12 GHz and could be swept across this entire range. Just the ticket for radar jammers.....just a bit to heavy to put in your car. The HP686C sweeper weighs in at over 100 pounds. The large rack mounted spectrum analyzer was far heavier.
That little tube... is tempting... yes tempting... for my little amplifier. Two of those should be enough to fill my room with soft music.
High power RF/radar transmitters are pretty much all vacuum-tube based, since they can handle upto megawatts with relative ease and high efficiency and I suspect are far more tolerant of VSWR and lightning issues than LDMOS based power amps.
And of course an electron microscope is just a sophisticated vacuum tube, as are various other scientific instruments.
They are actually very small compared to others with same output power, it also exist in 2 other versions, one for air cooling and one for water cooling, they are bigger. Price for one tube is about 800USD.
BTW, heater take 14V at 250A!
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My previous post was out of awe, rather than a mockery of an old technology. The beauty of these devices is their simplicity and their ability to handle extreme power ratings. Basically, thermionic valve technology, is using a vacuum to partially isolate electrodes exposed in the space of a stream of free electrons, which are boiled out of a metal cathode.
Building an amplifier out of such a behemoth device is truly tempting, at least, for myself. For a few amperes of cathode current, there should be no need of using the full heater power rating: at least, that is according to my logic, which given my inexperience in using valves, can easily be wrong. Boiled electrons require enough thermal energy to break free from their host atoms: this energy comes from the heater power. If a much much lower current is needed, less cooling of the cathode takes place, as less ionisation takes place.
I imagine a transformer based push-pull output with two such devices with local negative feedback at all amplification stages. But this is only a dream, the demands to do such a thing are quite high for my financial standing.
Building an amplifier out of such a behemoth device is truly tempting, at least, for myself. For a few amperes of cathode current, there should be no need of using the full heater power rating: at least, that is according to my logic, which given my inexperience in using valves, can easily be wrong. Boiled electrons require enough thermal energy to break free from their host atoms: this energy comes from the heater power. If a much much lower current is needed, less cooling of the cathode takes place, as less ionisation takes place.
I imagine a transformer based push-pull output with two such devices with local negative feedback at all amplification stages. But this is only a dream, the demands to do such a thing are quite high for my financial standing.
Wow, I didn't know about nutube, it looks amazing. Do you think it is useful to make a small guitar preamp?
That is its intended application. I believe that there are some commercial pedals and preamps out there that use the NuTube.
Go to the "instruments and amps" forum here on diyAudio and put NuTube into the "search this forum" box. Several people have discussed doing this, but I don't know if it's actually been done yet.
I prefer to play with 50 cent tubes rather than 50 dollar tubes, so I haven't tried the NuTube. When it first appeared they were $50 each, I have no idea what they cost today.
Go to the "instruments and amps" forum here on diyAudio and put NuTube into the "search this forum" box. Several people have discussed doing this, but I don't know if it's actually been done yet.
I prefer to play with 50 cent tubes rather than 50 dollar tubes, so I haven't tried the NuTube. When it first appeared they were $50 each, I have no idea what they cost today.