I have recorded the Vgs(off) and IDss of one hundred J201 JFET transistors taken from a reliable US source.
This could help you if you want to design some J201 based circuit and want to have a clear idea f what is out there.
For the measurements I have used a Peak Atlas DCA Pro (model DCA75) which is one of the best dedicated transistor meter on the market. It would help to give a constant set of values.
Small Bear Electronics J201 Transistors Measurement Vgs[off](V) Idss(mA)
J201 JFET no 01 -0.87 0.75
J201 JFET no 02 -0.95 0.87
J201 JFET no 03 -0.95 0.87
J201 JFET no 04 -0.76 0.60
J201 JFET no 05 -0.96 0.86
J201 JFET no 06 -0.89 0.77
J201 JFET no 07 -0.93 0.82
J201 JFET no 08 -0.93 0.81
J201 JFET no 09 -0.77 0.60
J201 JFET no 10 -0.85 0.71
J201 JFET no 11 -0.81 0.66
J201 JFET no 12 -0.65 0.45
J201 JFET no 13 -0.87 0.76
J201 JFET no 14 -0.74 0.58
J201 JFET no 15 -0.80 0.65
J201 JFET no 16 -0.73 0.57
J201 JFET no 17 -0.94 0.82
J201 JFET no 18 -0.97 0.86
J201 JFET no 19 -0.90 0.78
J201 JFET no 20 -0.81 0.67
J201 JFET no 21 -0.78 0.63
J201 JFET no 22 -0.65 0.45
J201 JFET no 23 -0.72 0.56
J201 JFET no 24 -0.82 0.68
J201 JFET no 25 -0.93 0.85
J201 JFET no 26 -0.84 0.69
J201 JFET no 27 -0.82 0.68
J201 JFET no 28 -0.85 0.72
J201 JFET no 29 -0.85 0.71
J201 JFET no 30 -0.73 0.55
J201 JFET no 31 -0.82 0.69
J201 JFET no 32 -0.85 0.70
J201 JFET no 33 -0.94 0.86
J201 JFET no 34 -0.91 0.79
J201 JFET no 35 -0.72 0.55
J201 JFET no 36 -0.96 0.87
J201 JFET no 37 -0.79 0.63
J201 JFET no 38 -0.74 0.57
J201 JFET no 39 -0.85 0.72
J201 JFET no 40 -0.78 0.62
J201 JFET no 41 -0.76 0.58
J201 JFET no 42 -0.83 0.68
J201 JFET no 43 -0.96 0.83
J201 JFET no 44 -0.82 0.69
J201 JFET no 45 -0.73 0.57
J201 JFET no 46 -0.90 0.78
J201 JFET no 47 -0.95 0.86
J201 JFET no 48 -0.73 0.56
J201 JFET no 49 -0.95 0.85
J201 JFET no 50 -0.96 0.85
J201 JFET no 51 -0.73 0.57
J201 JFET no 52 -0.73 0.57
J201 JFET no 53 -0.88 0.76
J201 JFET no 54 -0.92 0.83
J201 JFET no 55 -0.92 0.85
J201 JFET no 56 -0.93 0.84
J201 JFET no 57 -0.70 0.55
J201 JFET no 58 -0.87 0.78
J201 JFET no 59 -0.87 0.79
J201 JFET no 60 -0.89 0.80
J201 JFET no 61 -0.77 0.64
J201 JFET no 62 -0.91 0.80
J201 JFET no 63 -0.72 0.59
J201 JFET no 64 -0.72 0.57
J201 JFET no 65 -0.89 0.80
J201 JFET no 66 -0.83 0.72
J201 JFET no 67 -0.76 0.64
J201 JFET no 68 -0.80 0.69
J201 JFET no 69 -0.84 0.73
J201 JFET no 70 -0.84 0.69
J201 JFET no 71 -0.76 0.62
J201 JFET no 72 -0.80 0.67
J201 JFET no 73 -0.82 0.68
J201 JFET no 74 -0.91 0.79
J201 JFET no 75 -0.97 0.88
J201 JFET no 76 -0.74 0.58
J201 JFET no 77 -0.74 0.58
J201 JFET no 78 -0.86 0.75
J201 JFET no 79 -0.82 0.73
J201 JFET no 80 -0.74 0.60
J201 JFET no 81 -0.61 0.46
J201 JFET no 82 -0.90 0.78
J201 JFET no 83 -0.72 0.54
J201 JFET no 84 -0.86 0.69
J201 JFET no 85 -0.71 0.55
J201 JFET no 86 -0.99 0.84
J201 JFET no 87 -0.89 0.81
J201 JFET no 88 -0.92 0.88
J201 JFET no 89 -0.78 0.63
J201 JFET no 90 -0.94 0.88
J201 JFET no 91 -0.89 0.73
J201 JFET no 92 -0.78 0.58
J201 JFET no 93 -0.94 0.81
J201 JFET no 94 -0.83 0.67
J201 JFET no 95 -0.92 0.83
J201 JFET no 96 -0.90 0.80
J201 JFET no 97 -0.91 0.82
J201 JFET no 98 -0.95 0.80
J201 JFET no 99 -0.90 0.78
J201 JFET no 100 -0.94 0.83
Average Value -0.834V 0.704mA
Tayda Electronics J201 Transistors Measurement Vgs[off](V) Idss(mA)
J201 JFET no 01 -0.91 0.8
J201 JFET no 02 -0.93 0.82
J201 JFET no 03 -0.79 0.62
J201 JFET no 04 -0.74 0.59
J201 JFET no 05 -0.81 0.63
Average Value -0.84V 0.71mA
These are a set of screen shots you can take using the Peak DCA Pro software, they show the Id vs Vds and the Id vs Vgs plots. I did them overlaying the measurements of 4 different J201 JFET transistors, to prove that the graphs are pretty consistent.
Conclusion:
The average values after reading 100 JFETs are:
- Vgs(off) = -0.83V
- Idss = 0.70mA
This values are very close to the ones measured by Run off Groove (Vgs(off)=-0.84V and Idss=0.64mA) in his great article
A closer look at the Fetzer Valve.
The components tested above are from
Small Bear Electronics, a reliable US components supplier. I also ordered 5 transistors from
Tayda Electronics, in internet forums
[1] [2] some folks were questioning this components, not being sure of getting fake parts or relabeled transistors.
From my measurements and as far as I know the J201 from Tayda are good and within the datasheet specifications with average values also very close to the expected ones (Vgs(off)=-0.84V and Idss=0.71mA)