Yeah, that tube has pretty high gm.
Still leave out the capacitors across the 1.5k, and then also remove the fet and change the 25R to 1.5k.
The DCV at the lower plate should now be ~142VDC.
Still leave out the capacitors across the 1.5k, and then also remove the fet and change the 25R to 1.5k.
The DCV at the lower plate should now be ~142VDC.
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I agree with @rayma
Ditch the FET.
And get some current flowing!
I spec a 450V cap because beople might just buy a cheap cap and that way it'll last longer. You really just need a good 350V cap
Ditch the FET.
And get some current flowing!
I spec a 450V cap because beople might just buy a cheap cap and that way it'll last longer. You really just need a good 350V cap
That's where this comes in: Seriously, this is my go-to "I need HV" module. 12V in, 280V out. No noise if used properly. Isolated, affordable. Give it sh*t noisy power, it'll be noisy - it's not regulated. It's a dumb supply that just happens to work.
https://www.aliexpress.com/item/1005004887568336.html
https://www.aliexpress.com/item/1005004887568336.html
Thank you for your generous recommendations. What is the desired VDC at pin 1?
What you do not see in my schematic is the 100k input pot, and the 24.6K plate/dropping resistor where your 620R is. And, there is already a 220uF/450VDC decoupler :~)
What you do not see in my schematic is the 100k input pot, and the 24.6K plate/dropping resistor where your 620R is. And, there is already a 220uF/450VDC decoupler :~)
If you don't use the fet, and the two cathode resistors are equal (like in post #5),
then the Vpk voltages of the two tubes will be equal (within tolerances).
In other words, the plate voltage of the lower tube should be half of the supply voltage,
whatever that is.
then the Vpk voltages of the two tubes will be equal (within tolerances).
In other words, the plate voltage of the lower tube should be half of the supply voltage,
whatever that is.
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Pin 1 is a plate but so is pin 6, pin 9 is the internal shield which is usually grounded so depending on which triode is which, it would be full B+ or B+/2
I was referring to 6N6P.
Now I see what you are asking.
I usually aim for 250V at the top plate but my latest build used 300V and you could go as low as 200V I would think. Therefore the difference from pin 1 to 9 would be 125V or 150V or 100V on a 5687.
The 5687 has an H-K rating of only 90V though. Most people would advise elevating the heaters. I have never elevated a heater and the only tube I ever had develop an HK short was a 6N3P. I found that one amp I built uses a 6F12P for the input and cathodyne and it's cathode sits at 165V while the maximum rating is 100V. Several years 24/7 and no failures though.
YMMV and I don't use 5687 (because 6N6P are effectively the same and cheaper - same pinout as 6DJ8) anymore but I still have a pair of them
Now I see what you are asking.
I usually aim for 250V at the top plate but my latest build used 300V and you could go as low as 200V I would think. Therefore the difference from pin 1 to 9 would be 125V or 150V or 100V on a 5687.
The 5687 has an H-K rating of only 90V though. Most people would advise elevating the heaters. I have never elevated a heater and the only tube I ever had develop an HK short was a 6N3P. I found that one amp I built uses a 6F12P for the input and cathodyne and it's cathode sits at 165V while the maximum rating is 100V. Several years 24/7 and no failures though.
YMMV and I don't use 5687 (because 6N6P are effectively the same and cheaper - same pinout as 6DJ8) anymore but I still have a pair of them
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