loadline calculator
In other news, I found this handy loadline calculator. To my surprise, it even included the 6P30B tube! One cool thing is it adjusts the curves based on screen voltage, so it's more accurate than using the tube book curves which are only accurate for one voltage.
My first attempts produced a loadline that was mostly above the max dissipation. Eventually I realized the 8,500 ohm primary on my output transformer was causing this. I decided I will put a 16 ohm speaker on the 8 ohm secondary to reflect 17,000 ohm on the primary and keep my loadline just below max dissipation. see attached.
In other news, I found this handy loadline calculator. To my surprise, it even included the 6P30B tube! One cool thing is it adjusts the curves based on screen voltage, so it's more accurate than using the tube book curves which are only accurate for one voltage.
My first attempts produced a loadline that was mostly above the max dissipation. Eventually I realized the 8,500 ohm primary on my output transformer was causing this. I decided I will put a 16 ohm speaker on the 8 ohm secondary to reflect 17,000 ohm on the primary and keep my loadline just below max dissipation. see attached.
screen current
I think I got it..... from the Valve Wizard, "As a rule of thumb, screen current is a fixed ratio of the anode current. The EF86 data sheet tells us that for an anode current of 3.0mA, screen current is 0.6mA. This is a ratio of:
3.0 / 0.6 = 5.
In other words, the screen current will normally be about one fifth of the anode current, as long as we're operating well away from the knee of the curves."
The characteristics of 6P30B state anode current of 35 and g2 current of 1.3. That's approx 27:1 ratio. I'm now planning to run 15mA @ 300V anode, so that would be about 0.5mA g2 current. At peak, the grid current will be about 2.0mA.
Replacing R2 with 8.5K keeps voltages @ A-300, B-270, C-240. When the current steps up to 2mA B&C drop about 12 volts. see attached.
I think I got it..... from the Valve Wizard, "As a rule of thumb, screen current is a fixed ratio of the anode current. The EF86 data sheet tells us that for an anode current of 3.0mA, screen current is 0.6mA. This is a ratio of:
3.0 / 0.6 = 5.
In other words, the screen current will normally be about one fifth of the anode current, as long as we're operating well away from the knee of the curves."
The characteristics of 6P30B state anode current of 35 and g2 current of 1.3. That's approx 27:1 ratio. I'm now planning to run 15mA @ 300V anode, so that would be about 0.5mA g2 current. At peak, the grid current will be about 2.0mA.
Replacing R2 with 8.5K keeps voltages @ A-300, B-270, C-240. When the current steps up to 2mA B&C drop about 12 volts. see attached.
Attachments
I don't understand why it says that. It gives reasonable numbers for 6V6, but the 6P30B plots may be wrong.
I double-checked it manually, it was spot on. Apparently, the 6P30B has approximately 8500 ohm load resistance @ 300V.
I was hoping to get 12 watts out of it, now it's gonna be 8-9 watts I think, but that's still pretty good for lil bitty tubes!
Attachments
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I had not realized the 6p30b is a 5-watt tube, not the 12-watt job normally used in a "DeLuxe".
Then yes for similar supply at much lower power we need a much higher load value.
It also seems to want a Vg2 more like 120V.
https://frank.pocnet.net/sheets/113/6/6P30B.pdf
Then yes for similar supply at much lower power we need a much higher load value.
It also seems to want a Vg2 more like 120V.
https://frank.pocnet.net/sheets/113/6/6P30B.pdf
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I was looking back at this topic as I'm curently working on a build with the tube in question, and I felt it was important to note that there's 2 models:
6P30B, which is physically almost identical to a 5902;
6P30B-R/6P30B-ER, a larger bottle, dual-plate tube with a whopping 0,5w more plate dissipation.
According to this page denoting datasheet info for both models, they can withstand up to 250v, and 120v seems to simply be a suggested application.
I'm currently running my test build (Ra=3.8k, Rk=330R) at 115v, just to be safe. Getting plenty of volume.
With some extrapolations using vtadiy's Loadline Calculator, you can see this stage getting slightly over a watt of clean output, Single Ended.
Heck, with half the load and a smaller Rk, I could (theoretically) get nearly 2W. How well will that translate into the real world, I don't know.
6P30B, which is physically almost identical to a 5902;
6P30B-R/6P30B-ER, a larger bottle, dual-plate tube with a whopping 0,5w more plate dissipation.
According to this page denoting datasheet info for both models, they can withstand up to 250v, and 120v seems to simply be a suggested application.
I'm currently running my test build (Ra=3.8k, Rk=330R) at 115v, just to be safe. Getting plenty of volume.
With some extrapolations using vtadiy's Loadline Calculator, you can see this stage getting slightly over a watt of clean output, Single Ended.
Heck, with half the load and a smaller Rk, I could (theoretically) get nearly 2W. How well will that translate into the real world, I don't know.
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