Keysight U1401B User's And Service Manual

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Keysight U1401B User's And Service Manual Manual pdf 116 page image

5 Application Examples116 Keysight U1401B User’s and Service GuideJunction Field-Effect Transistor (JFET) Switch TestA JFET typically has three terminals, namely drain (D), gate (G), and source (S).There are two types of JFET depending on the channel type: p-channel andn-channel. It is recommended that you obtain the specific data sheet from themanufacturers. You can also use the U1401B to identify a JFET by following theprocedure below:1 Turn the rotary switch to the position.2 Connect the red and black test leads to the positive and negative inputterminals respectively. The positive terminal will provide a positive test voltage.3 In this example, we will use a JFET with TO-92 package as shown inFigure 5-10.Figure 5-10 TO-92 JFET4 Probe pin 1 with the red test lead, and pin 2 with the black test lead. Thenreverse the test leads and obtain the reading. If both readings are <1 kΩ, youcan assume that these pins are the drain and source terminals. The remainingpin 3 is the gate terminal. Always find out first which pin is the gate terminal.Refer to Table 5-7 on page 117.Most TO-92 JFETwill have pin 1 asthe drain.