I've been looking at this kit. Mostly because I need something for my workshop but also because I have the valves and transformer already.
Assuming I have a correct schematic, I have a couple of questions:
1. Shouldn't there be a coupling capacitor before the grid of the output valve?
2 The blurb says its possible to use 6080 valves on the output stage but considering they are famous for having a 3A heater filament - that would be a short cut to little mushroom cloud from the lt317 regulator wouldn't it?.
I'm still learning here so any help would be greatly appreciated.
Assuming I have a correct schematic, I have a couple of questions:
1. Shouldn't there be a coupling capacitor before the grid of the output valve?
2 The blurb says its possible to use 6080 valves on the output stage but considering they are famous for having a 3A heater filament - that would be a short cut to little mushroom cloud from the lt317 regulator wouldn't it?.
I'm still learning here so any help would be greatly appreciated.
An externally hosted image should be here but it was not working when we last tested it.
Thats the first time I have seen this DC BLOCKING capacitors are used to prevent high voltage DC currents affecting the next stage so that only the AC signal passes through (DC bias settings ) .
In tube radios faulty coupling capacitors are a common cause of no radio signal and I have also seen spectacular "blowups " in short-circuited coupling capacitors ruining the elements in the following tube stage.
In tube radios faulty coupling capacitors are a common cause of no radio signal and I have also seen spectacular "blowups " in short-circuited coupling capacitors ruining the elements in the following tube stage.
No.
Chinese 6N5P have 2.4A filament, which is overkill for lt317 too.
Well, you can do the cathode follower both ways, DC or AC coupled. The second way just requires the extra parts (capacitor and two resistors per channel).
the output stage is common cathode and so the directly connected grid is correct.
i have never had any problems with AC heaters
i have never had any problems with AC heaters
Well after all this approval of a DC connected tube stage to the grid of the next tube stage I am sure all the proponents of this can supply me with actual college or university documents that are taught to electronic engineers and electrical engineers to student looking to obtain diplomas/university degrees in both subjects .
I am not talking of he said this or that or ---"this works " I am talking of actual USA/UK degree courses authorized by those institutions via government approval as part of both those organizations approved courses in the teaching of students .
In other words-
The USA= the IEEE-USA.
The UK=IEE.
or even the IEC .
Supply me with REAL college/ university documents and I will accept it as normal practice in stage to stage tube/valve theory.
I am not talking of he said this or that or ---"this works " I am talking of actual USA/UK degree courses authorized by those institutions via government approval as part of both those organizations approved courses in the teaching of students .
In other words-
The USA= the IEEE-USA.
The UK=IEE.
or even the IEC .
Supply me with REAL college/ university documents and I will accept it as normal practice in stage to stage tube/valve theory.
duncan2, that's not the first time I see you demanding that others prove something to you. Like we care even the slightest bit if you personally accept something or not 🙂
DC coupled cathode followers are used in literally thousands of designs, both commercial and DIY. They have their advantages and disadvantages that should be taken into the consideration in each particular case, of course. If you don't like them - don't use them.
DC coupled cathode followers are used in literally thousands of designs, both commercial and DIY. They have their advantages and disadvantages that should be taken into the consideration in each particular case, of course. If you don't like them - don't use them.
Is "Valley & Wallman, Vacuum tube amplifiers" from MIT good enough? Look in chapter 11 Direct Coupled Amplifiers and you can learn how DC coupling is done.
Almost all professional books on tubes discuss DC coupling
In other contributions on diyAudio you present yourself as someone who has been repairing tube radio’s for decades and as knowing a thing or two about (tube) electronics.
But something does not seem right when looking at some of your postings:
- Discussing a schematic with a dc-coupled cathode follower but not making remarks about that, and repairing Tektronix equipment with 6080’s in it, which often has dc-coupling in them:
Headphone Amp Kit using 5670 + 6080 tubes - suggestions
- Knowing the circuit of the Fisher X-101D which has dc-coupled cathodyne phase-splitters:
Center Channel Stereo Tube Amp
- Knowing the classic Mullard designs (the famous Mullard 5-20 has a dc-coupled LTP phase-splitter) and knowing about Morgan Jones for about 40 years:
Shock! Mullard preamp.Heeelp!
- Repairing tube radio’s for decades but never heard of using the suppressor grid for something else than suppression (for instance: as a diode):
GU50 amp triode mode single end
- Posting part of the schematic of the HP 400AB Voltmeter with dc-coupling all around and stating that he is new to all this, which is hard to combine with repairing Tektronix equipment with 6080’s in it:
HP 400AB voltmeter rehab
No point, duncan2. You lack the education necessary to be able to understand the concepts involved. This is why you demand other people do the work for you.