You won't find any. The plain tetrode suffers from secondary emission that puts a 'kink' in the plate current / voltage curve at low plate voltages. This was cured by adding either a beam plate (to make a beam tetrode, e.g. 6V6, 6L6, 807, 6550, KT66, KT77, KT88, KT90) or a third grid (to make a pentode, e.g. EL84, EL34). All multigrid output tubes are either beam tetrodes or pentodes.
Hi nhuwar , Hi ray moth ,
There is ( or there was ) a very interesting PURE
TETRODE made for AF Class AB1 or AB2 amplifier .
( among many uses ) .
It have two PURE TETRODES into the same envelope ,
made initially by Telefunken , I never see it , anytime ,
in any place , but I have two NOS of them on my shelf .
Don’t ask me about the sound quality , because I didn’t
build anything with us .
The two PURE TETRODES into the same envelope , allow
us to build a push-pull amplifier , with only ONE tube at the
output .
More information on the FRANK’s site – code # 6360
See page 5 of Telefunken 6360 datasheet .
Interesting to see and to know !!
Regards ,
Carlos
There is ( or there was ) a very interesting PURE
TETRODE made for AF Class AB1 or AB2 amplifier .
( among many uses ) .
It have two PURE TETRODES into the same envelope ,
made initially by Telefunken , I never see it , anytime ,
in any place , but I have two NOS of them on my shelf .
Don’t ask me about the sound quality , because I didn’t
build anything with us .
The two PURE TETRODES into the same envelope , allow
us to build a push-pull amplifier , with only ONE tube at the
output .
More information on the FRANK’s site – code # 6360
See page 5 of Telefunken 6360 datasheet .
Interesting to see and to know !!
Regards ,
Carlos
I asked the same question a while back: http://www.diyaudio.com/forums/showthread.php?s=&threadid=86203&highlight=
Simon
Simon
EC8010 said:
Hi EC 8010 ,
Are you sure about that ???
I’m not sure , because over the entire bibliography available ,
the 6360 tube is mentioned and explicited how being a pure
tetrode , without beam plates or other tricks .
I , really , don’t want to broke the envelope of my NOS 6360
to confirm who has the reason !!! Or , if it is “impure” as
SY said !!!
Regards ,
Carlos
Klimon said:
I think it is important to read that - pretty well explains the lot.
Just to reiterate here: In the classic beam tetrode G3 was not rendered unnecessary by the use of beam forming plates (they do not act as suppressors). The important difference lies in the fact that a critical distance of plate-G2 is maintained, thus creating a space charge of electrons acting like a G3 when required. (This is greatest at the bottom swing of the plate, disappearing when the plate voltage go higher than that of G2. This somewhat adds to the efficiency, since in the pentode there is always a G3 "in the way" although the effect will be small.)
The beam forming electrodes are simply necessary to prevent stray electrons from reaching the G2 structures at the extremities, thus upsetting the operation. Again the descriptions appear to be rather liberal. The beam tube is in reality also a tetrode (in its operating area), but with the mentioned advantage of aligned grids apart from the above mentioned aspect.
Old hat, but just to refresh memories.
Regards
So what about the 4-*** class of electrodes from eimac. These are classified as a radial beam power tetrode. Are these tube still susceptible to secondary emission also.
Not that it matter I've decided to go with 3-500zg's but I still have a 4pr400a a on hand and I need a good amp for my bass.
Not that it matter I've decided to go with 3-500zg's but I still have a 4pr400a a on hand and I need a good amp for my bass.
I attempted to build a push pull amp using 4CX250's at 1KV a long time ago. I never could get it to work right, but it was back before I really knew what I was doing. I still have the remains of the amp around somewhere, but I don't think I will ever get around to experimenting further. I still have tubes for it too. I used up all of my 4PR400's building RF amplifiers in the mid 70's.
I have seen data on some RF tetrodes used in "Hi Mu Triode" mode. G1 and G2 are tied together and used as the control grid. A2 operation and serious grid current are required. I tried this with the typical audio pentodes and it doesn't work. It works OK with some sweep tubes, but I havent tried it with the 4CX250's yet.
I have several 833A's and all of the parts, a 200 watt SE guitar amp will get built when I have the time. I have already prototyped it and it positively rocks!
I have seen data on some RF tetrodes used in "Hi Mu Triode" mode. G1 and G2 are tied together and used as the control grid. A2 operation and serious grid current are required. I tried this with the typical audio pentodes and it doesn't work. It works OK with some sweep tubes, but I havent tried it with the 4CX250's yet.
I have several 833A's and all of the parts, a 200 watt SE guitar amp will get built when I have the time. I have already prototyped it and it positively rocks!
Sound like we think alike.
I've got most of my knowledge from working around rf got ton's of tubes for rf from 10kw tube to even 1 2.5 megawatt tube to bad it microwave tube.
I just figuare my bodies absorbed enough radiation it's time to give my ear's a turn and what better to do it then with 2 800 watt single ended triode amps that I built.
I've got most of my knowledge from working around rf got ton's of tubes for rf from 10kw tube to even 1 2.5 megawatt tube to bad it microwave tube.
I just figuare my bodies absorbed enough radiation it's time to give my ear's a turn and what better to do it then with 2 800 watt single ended triode amps that I built.
I learned electronics by taking things apart. Very few things ever got put back together. Fortunately in the 60's vacuum tube things (radios, TV's and HiFi sets) were available in large quantities for free in the trash. By age 14 I was building guitar amps from TV parts. Some worked good, many blew up at power on, most were in between, but I learned a lot this way.
In 1973, I got a job at a major electronics manufacturing plant where I still work today, first as a factory RF technician, and for the last 20 years an RF engineer.
Combine tubes with RF engineering, and you get RF amplifiers, big RF amplifiers. I got a bunch of 4PR400's when some CO2 lasers were scrapped out. Run in class C you can get almost 1KW out of 1 tube if you ignore that pesky orange glow. Sometime in the 1970s, I got a bunch of 4CX150's, 4CX250's, 4CX350's and sockets from military surplus. I got some big power transformers too. That started the BIG audio amp experiments. I played with the 4CX250's and I got distortion, lots of distortion. I wound up using sweep tubes in parallel push pull and the amp eventually worked. Looking back I am 90% certain that the amp was oscillating, but I will never know, since it has been robbed for almost every useful part.
A few years ago, I traded a few days of work for a semi load of vacuum tubes. I was told in advance that tube dealers had already taken "all of the useful tubes". I have found 20 working 833A's, 4 NOS RCA 845's and over 100 5842's. I have also found lots of WWII era transmitting tubes, and have been experimenting with them for audio uses. I can't find my notes but I ran across a tube specified for "Hi Mu Triode connection".
In 1973, I got a job at a major electronics manufacturing plant where I still work today, first as a factory RF technician, and for the last 20 years an RF engineer.
Combine tubes with RF engineering, and you get RF amplifiers, big RF amplifiers. I got a bunch of 4PR400's when some CO2 lasers were scrapped out. Run in class C you can get almost 1KW out of 1 tube if you ignore that pesky orange glow. Sometime in the 1970s, I got a bunch of 4CX150's, 4CX250's, 4CX350's and sockets from military surplus. I got some big power transformers too. That started the BIG audio amp experiments. I played with the 4CX250's and I got distortion, lots of distortion. I wound up using sweep tubes in parallel push pull and the amp eventually worked. Looking back I am 90% certain that the amp was oscillating, but I will never know, since it has been robbed for almost every useful part.
A few years ago, I traded a few days of work for a semi load of vacuum tubes. I was told in advance that tube dealers had already taken "all of the useful tubes". I have found 20 working 833A's, 4 NOS RCA 845's and over 100 5842's. I have also found lots of WWII era transmitting tubes, and have been experimenting with them for audio uses. I can't find my notes but I ran across a tube specified for "Hi Mu Triode connection".
I got my experience working on t.v. transmitters but I'm in the material science field. I'm going back to school to get my e.e. though so I can make this more then a hobby.
Sounds like you got quite the stash of so killer tube. The 833a was one of my choices for the amp i'm building but it have to high of a output impedence.
Good rf tube though
Sounds like you got quite the stash of so killer tube. The 833a was one of my choices for the amp i'm building but it have to high of a output impedence.
Good rf tube though
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