It seems no one qualify for screen drive...
As Far As I know 6P31s is common to EL36.
That 6P31S data comes from what appears to be triode data on the right side, bottom, of the last data page, some obvious typos make it confusing. So it likely has the same issue as the EL36 datasheet, in either removing the effect of 170 Vp from the triode curves, or using the left bottom side curves, which have -1V on g1 effects that needs fixing up. So probably more like 420 mA at 150V on g2, like the EL36.
http://frank.pocnet.net/sheets/113/6/6P31S.pdf
Easy enough to test one, just put +60V on the plate, and momentarily +150V on g2, and measure the cathode current.
http://frank.pocnet.net/sheets/113/6/6P31S.pdf
Easy enough to test one, just put +60V on the plate, and momentarily +150V on g2, and measure the cathode current.
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Yes, these PL508's are very nice looking tubes, especially those with their evacuation tip between their pins. And they're still cheap.
But what is the arrangement around that IRFP460 good for? I think that there's no need for a regulated power supply for a PP power amp.
Which plate-to-plate load does your output tranny provide?
Best regards, Uwe
But what is the arrangement around that IRFP460 good for? I think that there's no need for a regulated power supply for a PP power amp.
Which plate-to-plate load does your output tranny provide?
Best regards, Uwe
I was testing a 36MC6 on the curve tracer versus a 35LR6 and found it had a higher knee current than the -LR6. So I went back and compared data sheets and found the 6LR6 datasheet has an error on it. The g2 = 150V curve is actually the 160V curve. So 150 V knee current for the 6LR6 is actually more like 1085 mA. (so taking it out of 1st place)
Revised list of knee currents for g2 = 150 V, g1 = 0 V, Vp = 60 to 70 V
<tube> <mA knee> <Watt rating> <mA/Watt> <registered by>
6LF6 1144 40W 28.6 Amperex
6KG6/EL509 1135 34W 33.4 Amperex
6MC6 1130 33W 34.2 RCA
13E1 1120 90W 12.4 AEI
6MH6 1100 38.5W 28.6 GE (up-rated 6LX6,6KD6,26HU5)
6LR6 1085 30W 36.1 Sylvania
6MB6 1080 35W 30.9 Sylvania
6LX6/6KD6/26HU5 1080 33W 33 GE
6LW6 1050 40W 26.3 GE
6KN6 1050 30W 35 Sylvania (later versions are 6KD6)
6LZ6 940 30W 31 RCA
6LB6 825 30W 27.5 GE
6JE6C/6JS6C 789 30W 26.3 Sylvania
6JE6 762 24W 32 RCA
6JS6/6HF5 749 28W 27 GE
6MJ6 740 30W 24.6 RCA
6LG6 740 28W 26.4 GE
6LQ6 715 30W 24 RCA
6ME6 700 30W 23.3 RCA
6DQ5 690 24W 29 RCA
6JF6/6JG6 660 17W 39 RCA
6KM6 630 20W 31.5 RCA
6HJ5 630 24W 26.2 Raytheon
6JR6/6JU6 600 17W 35.3 RCA
6JZ6/21HB5A 560 18W 31 GE
12HE7 540 10-15W 36 Sylvania (15W if damper disabled)
6CL5 520 25W 20.8 Sylvania
6GB5/29KQ6/EL500 500 17W 29.4 Amperex
6KV6A 488 (630?) 20-28W 24.4-31.5 RCA (re-rated 6KM6?)
6HB5/6GY5/6KE6/16KA6/21JV6 475 18W 26.4 GE
6EX6 460 22W 21 Raytheon (up-rated 6CD6)
6CB5/A 440 23/26W 17 RCA
6CD6/GA 422 15/20W 21 RCA
6GT5/6GJ5/6JT6/6GW6/6JB6 380 17.5W 21.7 RCA
6GE5 350 17.5W 20 GE
6GF5 345 9W 38.3 GE
6JM6/6JN6/6FW5/6GC6 340 17.5/18W 19.4 GE
6DQ6B/6GV5 330 17.5/18W 18.3 GE
6DQ6A 280 18W 15.5 RCA
6JA5/10JA5 276 19W 14.5 GE
6LU8/6LR8/6MY8 265 14/16W 19 Sylvania
6AV5GA/6BQ6GA 255 11W 23 GE, CBS
KT120 221 60W 3.7
KT90 220 50W 4.4
6550A 190 35W 5.4
KT88 170 35W 4.9
6GK6 84 13.2W 6.4 Sylvania
6JC5 80 19W 4.2 Sylvania
6L6GC 75 30W 2.5 RCA
6HB6 70 10W 7 Raytheon
6V6GA 45 14W 3 CBS
Revised list of knee currents for g2 = 150 V, g1 = 0 V, Vp = 60 to 70 V
<tube> <mA knee> <Watt rating> <mA/Watt> <registered by>
6LF6 1144 40W 28.6 Amperex
6KG6/EL509 1135 34W 33.4 Amperex
6MC6 1130 33W 34.2 RCA
13E1 1120 90W 12.4 AEI
6MH6 1100 38.5W 28.6 GE (up-rated 6LX6,6KD6,26HU5)
6LR6 1085 30W 36.1 Sylvania
6MB6 1080 35W 30.9 Sylvania
6LX6/6KD6/26HU5 1080 33W 33 GE
6LW6 1050 40W 26.3 GE
6KN6 1050 30W 35 Sylvania (later versions are 6KD6)
6LZ6 940 30W 31 RCA
6LB6 825 30W 27.5 GE
6JE6C/6JS6C 789 30W 26.3 Sylvania
6JE6 762 24W 32 RCA
6JS6/6HF5 749 28W 27 GE
6MJ6 740 30W 24.6 RCA
6LG6 740 28W 26.4 GE
6LQ6 715 30W 24 RCA
6ME6 700 30W 23.3 RCA
6DQ5 690 24W 29 RCA
6JF6/6JG6 660 17W 39 RCA
6KM6 630 20W 31.5 RCA
6HJ5 630 24W 26.2 Raytheon
6JR6/6JU6 600 17W 35.3 RCA
6JZ6/21HB5A 560 18W 31 GE
12HE7 540 10-15W 36 Sylvania (15W if damper disabled)
6CL5 520 25W 20.8 Sylvania
6GB5/29KQ6/EL500 500 17W 29.4 Amperex
6KV6A 488 (630?) 20-28W 24.4-31.5 RCA (re-rated 6KM6?)
6HB5/6GY5/6KE6/16KA6/21JV6 475 18W 26.4 GE
6EX6 460 22W 21 Raytheon (up-rated 6CD6)
6CB5/A 440 23/26W 17 RCA
6CD6/GA 422 15/20W 21 RCA
6GT5/6GJ5/6JT6/6GW6/6JB6 380 17.5W 21.7 RCA
6GE5 350 17.5W 20 GE
6GF5 345 9W 38.3 GE
6JM6/6JN6/6FW5/6GC6 340 17.5/18W 19.4 GE
6DQ6B/6GV5 330 17.5/18W 18.3 GE
6DQ6A 280 18W 15.5 RCA
6JA5/10JA5 276 19W 14.5 GE
6LU8/6LR8/6MY8 265 14/16W 19 Sylvania
6AV5GA/6BQ6GA 255 11W 23 GE, CBS
KT120 221 60W 3.7
KT90 220 50W 4.4
6550A 190 35W 5.4
KT88 170 35W 4.9
6GK6 84 13.2W 6.4 Sylvania
6JC5 80 19W 4.2 Sylvania
6L6GC 75 30W 2.5 RCA
6HB6 70 10W 7 Raytheon
6V6GA 45 14W 3 CBS
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Added the date registered.
Revised list of knee currents for g2 = 150 V, g1 = 0 V, Vp = 60 to 70 V
<tube> <mA knee> <Watt rating> <mA/Watt> <registered by> <date>
6LF6 1144 40W 28.6 Amperex 1968
6KG6/EL509 1135 34W 33.4 Amperex 1965
6MC6 1130 33W 34.2 RCA (6LX6 clone) 1972
13E1 1120 90W 12.4 AEI 1961
6MH6 1100 38.5W 28.6 GE (up-rated 6LX6,6KD6,26HU5) 1972
6LR6 1085 30W 36.1 Sylvania 1968
6MB6 1080 38W 28.4 Sylvania 1971
6LX6/6KD6/26HU5 1080 33W 33 GE 1969/1965/1969
6LW6 1050 40W 26.3 GE 1971
6KN6 1050 30W 35 Sylvania (later versions are 6KD6) 1965
6LZ6 940 30W 31 RCA 1971
6LB6 825 30W 27.5 GE 1967
6JE6C/6JS6C 789 30W 26.3 Sylvania 68/69
6JE6 762 24W 32 RCA 1962
6JS6/6HF5 749 28W 27 GE 1964/1963
6MJ6 740 30W 24.6 RCA 1973
6LG6 740 28W 26.4 GE 1967
6LQ6 715 30W 24 RCA 1967
6ME6 700 30W 23.3 RCA 1971
6DQ5 690 24W 29 RCA 1957
6JF6/6JG6 660 17W 39 RCA 1965/1964
6KM6 630 20W 31.5 RCA 1965
6HD5/6HJ5 630 24W 26.2 Raytheon 1962/1963
6JR6/6JU6 600 17W 35.3 RCA 1968/1966
6JZ6/21HB5A 560 18W 31 GE 1966/1964
12HE7 540 10-15W 36 GE (15W if damper disabled) 1964
6CL5 514 25W 20.8 Sylvania 1955
6GB5/29KQ6/EL500 500 17W 29.4 Amperex 1961/Matsushita 1959/Philips 1961?
6KV6/A 610/488 20-28W 24.4-31.5 RCA (re-rated 6KM6?) 1967/1969
6HB5/6GY5/21JV6/6KE6/16KA6 475 18W 26.4 GE/GE/GE/Ray/Tung 1962/1962/1965/1965/1964
6EX6 460 22W 21 Raytheon (up-rated 6CD6) 1959
6CB5/A 440 23/26W 17 RCA 1954/1956
6CD6/GA 422 15/20W 21 RCA/GE 1949/1954
6GT5/6GJ5/6JT6/6JB6/6GW6 380 17.5W 21.7 RCA 1961/1961/1964/1962/1961
6GE5 350 17.5W 20 GE 1961
6GF5 345 9W 38.3 GE 1961
6JM6/6JN6/6FW5/6GC6 340 17.5/18W 19.4 GE 1964/1964/1960/1960
6DQ6B/6GV5 330 17.5/18W 18.3 GE 1959/1962
6DQ6/A 280 18W 15.5 CBS/RCA 1955/1956
6JA5/10JA5 276 19W 14.5 GE 1971
6LU8/6LR8/6MY8 265 14/16W 19 Sylvania 1964/1964/1970(Tungsol)
6AV5/GA///6BQ6/GA 255 11W 23 CBS/GE 1949/1955 /// CBS/Syl 1949/1953
KT120 221 60W 3.7
KT90 220 50W 4.4
6Y6G/GT/GA 200 12.5W Ray 1937/KenRad 1939/Syl 1954
6550A 190 35W 5.4
6W6GT 185 10W CBS 1939
KT88 170 35W 4.9
6CA7/EL34 107 25W 4.3 Philips 1952
6JC5 80 19W 4.2 Sylvania 1971
6L6/G/GA/GB/GC 77 30W 2.5 RCA 1936/Ray 1936/Syl 1943/Syl 1954/GE 1958
6HB6 70 10W 7 Raytheon 1961
6GK6 65 13.2W 5 CBS 1959
6BQ5/EL84 65 12W 5.4 Rogers 1956
6V6G/GT 45 14W 3 KenRad 1936/CBS 1939
Revised list of knee currents for g2 = 150 V, g1 = 0 V, Vp = 60 to 70 V
<tube> <mA knee> <Watt rating> <mA/Watt> <registered by> <date>
6LF6 1144 40W 28.6 Amperex 1968
6KG6/EL509 1135 34W 33.4 Amperex 1965
6MC6 1130 33W 34.2 RCA (6LX6 clone) 1972
13E1 1120 90W 12.4 AEI 1961
6MH6 1100 38.5W 28.6 GE (up-rated 6LX6,6KD6,26HU5) 1972
6LR6 1085 30W 36.1 Sylvania 1968
6MB6 1080 38W 28.4 Sylvania 1971
6LX6/6KD6/26HU5 1080 33W 33 GE 1969/1965/1969
6LW6 1050 40W 26.3 GE 1971
6KN6 1050 30W 35 Sylvania (later versions are 6KD6) 1965
6LZ6 940 30W 31 RCA 1971
6LB6 825 30W 27.5 GE 1967
6JE6C/6JS6C 789 30W 26.3 Sylvania 68/69
6JE6 762 24W 32 RCA 1962
6JS6/6HF5 749 28W 27 GE 1964/1963
6MJ6 740 30W 24.6 RCA 1973
6LG6 740 28W 26.4 GE 1967
6LQ6 715 30W 24 RCA 1967
6ME6 700 30W 23.3 RCA 1971
6DQ5 690 24W 29 RCA 1957
6JF6/6JG6 660 17W 39 RCA 1965/1964
6KM6 630 20W 31.5 RCA 1965
6HD5/6HJ5 630 24W 26.2 Raytheon 1962/1963
6JR6/6JU6 600 17W 35.3 RCA 1968/1966
6JZ6/21HB5A 560 18W 31 GE 1966/1964
12HE7 540 10-15W 36 GE (15W if damper disabled) 1964
6CL5 514 25W 20.8 Sylvania 1955
6GB5/29KQ6/EL500 500 17W 29.4 Amperex 1961/Matsushita 1959/Philips 1961?
6KV6/A 610/488 20-28W 24.4-31.5 RCA (re-rated 6KM6?) 1967/1969
6HB5/6GY5/21JV6/6KE6/16KA6 475 18W 26.4 GE/GE/GE/Ray/Tung 1962/1962/1965/1965/1964
6EX6 460 22W 21 Raytheon (up-rated 6CD6) 1959
6CB5/A 440 23/26W 17 RCA 1954/1956
6CD6/GA 422 15/20W 21 RCA/GE 1949/1954
6GT5/6GJ5/6JT6/6JB6/6GW6 380 17.5W 21.7 RCA 1961/1961/1964/1962/1961
6GE5 350 17.5W 20 GE 1961
6GF5 345 9W 38.3 GE 1961
6JM6/6JN6/6FW5/6GC6 340 17.5/18W 19.4 GE 1964/1964/1960/1960
6DQ6B/6GV5 330 17.5/18W 18.3 GE 1959/1962
6DQ6/A 280 18W 15.5 CBS/RCA 1955/1956
6JA5/10JA5 276 19W 14.5 GE 1971
6LU8/6LR8/6MY8 265 14/16W 19 Sylvania 1964/1964/1970(Tungsol)
6AV5/GA///6BQ6/GA 255 11W 23 CBS/GE 1949/1955 /// CBS/Syl 1949/1953
KT120 221 60W 3.7
KT90 220 50W 4.4
6Y6G/GT/GA 200 12.5W Ray 1937/KenRad 1939/Syl 1954
6550A 190 35W 5.4
6W6GT 185 10W CBS 1939
KT88 170 35W 4.9
6CA7/EL34 107 25W 4.3 Philips 1952
6JC5 80 19W 4.2 Sylvania 1971
6L6/G/GA/GB/GC 77 30W 2.5 RCA 1936/Ray 1936/Syl 1943/Syl 1954/GE 1958
6HB6 70 10W 7 Raytheon 1961
6GK6 65 13.2W 5 CBS 1959
6BQ5/EL84 65 12W 5.4 Rogers 1956
6V6G/GT 45 14W 3 KenRad 1936/CBS 1939
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Well, 4D32 looks like it is intended for + voltage on g1.
http://frank.pocnet.net/sheets/084/4/4D32.pdf
But using the graph on page 4, for the 0 V g1 curve, the knee is around 600 mA with 300 V on g2. With 150 V on g2, this would be reduced by (150/300)^1.5 = .3535 or 212 mA for the knee. You might however want to put some static + V on g1 instead. On page 1 it says the grid 1 - screen amplification factor is 10. For +15 V on g1 it would then take -150 V on g2 to turn it off. The +15 V on g1 is equivalent to another +150 V on g2. So +15 g1 and +150 g2 will give the same graph spacing as what is on page 4. Just that we use the 0 V g1 and +300 V g2 curve instead. So the knee will now be at about +600 mA. So the g2 drive will have to run +/1 150 V to control the 600 mA.
http://frank.pocnet.net/sheets/084/4/4D32.pdf
But using the graph on page 4, for the 0 V g1 curve, the knee is around 600 mA with 300 V on g2. With 150 V on g2, this would be reduced by (150/300)^1.5 = .3535 or 212 mA for the knee. You might however want to put some static + V on g1 instead. On page 1 it says the grid 1 - screen amplification factor is 10. For +15 V on g1 it would then take -150 V on g2 to turn it off. The +15 V on g1 is equivalent to another +150 V on g2. So +15 g1 and +150 g2 will give the same graph spacing as what is on page 4. Just that we use the 0 V g1 and +300 V g2 curve instead. So the knee will now be at about +600 mA. So the g2 drive will have to run +/1 150 V to control the 600 mA.
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"So the g2 drive will have to run +/- 150 V to control the 600 mA peak."
Problem though.
With -150 V on g2 and +15 V on g1, the g1 current may be excessive. This would have to be checked. +15 V on g1 is similar to +150 V on g2, so the cathode current should be around 212 mA.
212 mA x 15 V = 3 Watts on g1, which is within the 10 W rating for g1. I would still do a measurement just to be sure though. The g1 current will likely cause some significant non-linearity toward the - g2 V end unfortunately. Maybe not such a good idea. The usual g2 drive setups tend to use some small -V on g1, so maybe they are onto something about avoiding g1 current non-linearity.
"So the g2 drive will have to run +/- 150 V to control the 600 mA peak."
Problem though.
With -150 V on g2 and +15 V on g1, the g1 current may be excessive. This would have to be checked. +15 V on g1 is similar to +150 V on g2, so the cathode current should be around 212 mA.
212 mA x 15 V = 3 Watts on g1, which is within the 10 W rating for g1. I would still do a measurement just to be sure though. The g1 current will likely cause some significant non-linearity toward the - g2 V end unfortunately. Maybe not such a good idea. The usual g2 drive setups tend to use some small -V on g1, so maybe they are onto something about avoiding g1 current non-linearity.
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Hmmm, I may be over-estimating the g1 current problem on the 4D32. The negative g2 (-150 V) still has influence over the cathode current emission, which I left out above. So it will just be points along the cathode where g1 wires block the effect (view) of g2 that will have some residual emission. I guess this scenario calls for a static test with -150 V on g2 and +15 V on g1 to see how much g1 current there actually is.
One could also try a scaled drive setup with this tube. With the g2/g1 Mu of 10, use 10% of the drive signal (10% of the 300 V delta) on g1 and 50% of the drive signal (.5 x 300 V delta) on g2. Each grid does half the work this way and the required g2 voltage drive swing is cut in half.
A recent screen drive idea I came up with is to drive the g2 with a higher impedance (instead of direct V drive), and then use a 1/Mu resistive (high R) attenuator from the g2 voltage down to the g1 grid (and down to -V1bias for the bottom). The current drawn by the g2 grid ideally looks like a diode function. So the voltage developed at g2 would be the inverse of the 3/2 power V to I function (assuming the I input is linear to begin with), or 2/3 power I to V effectively on g2. Putting the attenuated 2/3 power voltage on the g1 then, linearizes its effect (2/3 x 3/2 power law) (assuming g1 is in negative territory, so no further current effect). So one "might" end up with linearized drive for the combo.
Reducing the g2 drive swing (using the 1/Mu scaled drives), works even better for a tube with a lower Mu, like the TV sweeps. A Mu of 4 tube would only require twice the usual g1 drive applied to g2, and half the usual g1 drive applied to g1.
One could also try a scaled drive setup with this tube. With the g2/g1 Mu of 10, use 10% of the drive signal (10% of the 300 V delta) on g1 and 50% of the drive signal (.5 x 300 V delta) on g2. Each grid does half the work this way and the required g2 voltage drive swing is cut in half.
A recent screen drive idea I came up with is to drive the g2 with a higher impedance (instead of direct V drive), and then use a 1/Mu resistive (high R) attenuator from the g2 voltage down to the g1 grid (and down to -V1bias for the bottom). The current drawn by the g2 grid ideally looks like a diode function. So the voltage developed at g2 would be the inverse of the 3/2 power V to I function (assuming the I input is linear to begin with), or 2/3 power I to V effectively on g2. Putting the attenuated 2/3 power voltage on the g1 then, linearizes its effect (2/3 x 3/2 power law) (assuming g1 is in negative territory, so no further current effect). So one "might" end up with linearized drive for the combo.
Reducing the g2 drive swing (using the 1/Mu scaled drives), works even better for a tube with a lower Mu, like the TV sweeps. A Mu of 4 tube would only require twice the usual g1 drive applied to g2, and half the usual g1 drive applied to g1.
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