Post by myles on Oct 14, 2008 10:43:43 GMT -7
EF86 test results on NOS and production tubes
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Here are some test results on various EF86 tubes. There are mostly NOS tubes here but some production tubes as well. Note that these vary widely from design spec in many cases.
These were tested using RCA/Mullard design spec which is 250 volts on the plates, 140 on the screen and a 2 volt bias
Expected results are 3.0mA plate current, 1800 transconductance and a gain of 38 in the test circuit. There are a number of amps made today that push these in their particular circuit to a gain of over 400 and microphonics can be a serious issue in those amps.
NOS tubes had a much longer service life and rejected physical microphonics much better over life testing than any current production tube.
Some amps such as the Dr. Z Z-28, Route 66, KT-45 and Delta 88 tolerate poor examples of this tube better than many other amps as the tube is not expected to produce as much gain as in some other amps as a sidenote.
In the rows below, the first number is plate current output, the second number is transconductance, the third number is not important for this report and the fourth number is true/actual gain in the design spec test circuit. Tube with high gain over spec in the area of 60+ would be very prone to physical microphonics in amps such as a Matchless DC-30.
These tubes vary widely. If you are in SoCal and have EF86 tubes you wish to have spec'd and curve traced I would be happy to do this for you until I leave SoCal for other places. I am on the road a lot these days so I may be closer to some of you in the future.
3.0 1800 38 Tesla - spec tube
3.2 1520 0.005 30.4 Tesla
4.1 2430 0.0045 54.0 Tesla
2.7 2030 0.002 101.5 Tesla
3.4 2160 0.005 43.2 Tesla
2.6 1950 0.002 97.5 Tesla
2.7 1920 0.003 64.0 Tesla
3.0 2060 0.004 38.1 Tesla - Reference tube
3.0 2140 0.003 71.3 Tesla
1.9 1710 0.002 85.5 Tesla
2.8 1990 0.0025 79.6 Tesla
2.4 1880 0.0025 75.2 Tesla
4.1 2460 0.004 61.5 Tesla
2.5 1700 0.002 85.0 Dario
2.6 1890 0.003 63.0 Tesla
3.8 1990 0.004 49.8 Tesla
2.9 1950 0.003 65.0 Tesla
2.7 1720 0.004 43.0 Dario
4.0 2130 0.006 35.5 Tesla
2.7 2030 0.003 67.7 Tesla
2.5 1640 0.003 54.7 Dario
2.3 1820 0.003 60.7 Covered / shrink wrapped
2.4 1840 0.003 61.3 Tesla Covered / shrink wrapped
2.7 2000 0.003 66.7 Covered / shrink wrapped
2.3 1680 0.004 42.0 Covered / shrink wrapped
3.5 2030 0.002 101.5 Dario
2.7 1600 0.003 53.3 Tesla
2.9 2050 0.004 51.3 Electro Harmonix
2.6 1740 0.002 87.0 Tesla
2.3 1810 0.0025 72.4 Tesla
3.5 2130 0.003 71.0 Dario
3.2 2070 0.004 51.8 Tesla
3.8 2240 0.002 112.0 Dario
3.2 1930 0.004 48.3 Svetlana winged C
3.7 2400 0.005 48.0 Tesla
3.1 1710 0.0045 38.0 Svetlana winged C - Good ref tube
2.3 1690 0.003 56.3 Svetlana winged C
2.4 1420 0.004 35.5 Dario
3.6 1900 0.0045 42.2 Svetlana winged C
3.1 1820 0.0045 40.4 Svetlana winged C
3.4 1900 0.003 63.3 Svetlana winged C
2.4 1650 0.003 55.0 Svetlana winged C
3.1 1990 0.005 39.8 Tesla
2.7 1930 0.004 48.3 Tesla
3.3 1720 0.006 28.7 Tesla
2.4 1850 0.002 92.5 Tesla
3.1 2050 0.004 51.3 Tesla
-end-
--------------------------------------------------------------------------------
Here are some test results on various EF86 tubes. There are mostly NOS tubes here but some production tubes as well. Note that these vary widely from design spec in many cases.
These were tested using RCA/Mullard design spec which is 250 volts on the plates, 140 on the screen and a 2 volt bias
Expected results are 3.0mA plate current, 1800 transconductance and a gain of 38 in the test circuit. There are a number of amps made today that push these in their particular circuit to a gain of over 400 and microphonics can be a serious issue in those amps.
NOS tubes had a much longer service life and rejected physical microphonics much better over life testing than any current production tube.
Some amps such as the Dr. Z Z-28, Route 66, KT-45 and Delta 88 tolerate poor examples of this tube better than many other amps as the tube is not expected to produce as much gain as in some other amps as a sidenote.
In the rows below, the first number is plate current output, the second number is transconductance, the third number is not important for this report and the fourth number is true/actual gain in the design spec test circuit. Tube with high gain over spec in the area of 60+ would be very prone to physical microphonics in amps such as a Matchless DC-30.
These tubes vary widely. If you are in SoCal and have EF86 tubes you wish to have spec'd and curve traced I would be happy to do this for you until I leave SoCal for other places. I am on the road a lot these days so I may be closer to some of you in the future.
3.0 1800 38 Tesla - spec tube
3.2 1520 0.005 30.4 Tesla
4.1 2430 0.0045 54.0 Tesla
2.7 2030 0.002 101.5 Tesla
3.4 2160 0.005 43.2 Tesla
2.6 1950 0.002 97.5 Tesla
2.7 1920 0.003 64.0 Tesla
3.0 2060 0.004 38.1 Tesla - Reference tube
3.0 2140 0.003 71.3 Tesla
1.9 1710 0.002 85.5 Tesla
2.8 1990 0.0025 79.6 Tesla
2.4 1880 0.0025 75.2 Tesla
4.1 2460 0.004 61.5 Tesla
2.5 1700 0.002 85.0 Dario
2.6 1890 0.003 63.0 Tesla
3.8 1990 0.004 49.8 Tesla
2.9 1950 0.003 65.0 Tesla
2.7 1720 0.004 43.0 Dario
4.0 2130 0.006 35.5 Tesla
2.7 2030 0.003 67.7 Tesla
2.5 1640 0.003 54.7 Dario
2.3 1820 0.003 60.7 Covered / shrink wrapped
2.4 1840 0.003 61.3 Tesla Covered / shrink wrapped
2.7 2000 0.003 66.7 Covered / shrink wrapped
2.3 1680 0.004 42.0 Covered / shrink wrapped
3.5 2030 0.002 101.5 Dario
2.7 1600 0.003 53.3 Tesla
2.9 2050 0.004 51.3 Electro Harmonix
2.6 1740 0.002 87.0 Tesla
2.3 1810 0.0025 72.4 Tesla
3.5 2130 0.003 71.0 Dario
3.2 2070 0.004 51.8 Tesla
3.8 2240 0.002 112.0 Dario
3.2 1930 0.004 48.3 Svetlana winged C
3.7 2400 0.005 48.0 Tesla
3.1 1710 0.0045 38.0 Svetlana winged C - Good ref tube
2.3 1690 0.003 56.3 Svetlana winged C
2.4 1420 0.004 35.5 Dario
3.6 1900 0.0045 42.2 Svetlana winged C
3.1 1820 0.0045 40.4 Svetlana winged C
3.4 1900 0.003 63.3 Svetlana winged C
2.4 1650 0.003 55.0 Svetlana winged C
3.1 1990 0.005 39.8 Tesla
2.7 1930 0.004 48.3 Tesla
3.3 1720 0.006 28.7 Tesla
2.4 1850 0.002 92.5 Tesla
3.1 2050 0.004 51.3 Tesla
-end-