Good info JJ, that's exactly what I needed. While the mosfets where in the board it looked like there was a short between pins, but it kinda drained like a capacitor. So I pulled one off the board and saw ~150ohm between drain and gate and 2Mohm
between source and gate.? Replaced both of them being careful to keep the tiny diode on the wire so I could maintain polarity.? Everything is back to the way it was!??
No idea what killed them, swr is never higher than 1.5 except for the brief moment when the tuner kicks in when switching bands.? Guess I better buy another set or two of spares!?
Now that I'm set to test if it is more stable, it's a massive CME weekend, all the bands are dead.? So I'll try again when that passes.
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Assuming you only have a multimeter, you can try this..
Shorted Pin Check
- Set your multimeter to the continuity or diode test mode.
- Check for shorts between each pair of pins (Gate-Drain, Gate-Source, Drain-Source).
- There should be no continuity between any of the pairs. A beep or low resistance reading indicates a short circuit, and likely a damaged MOSFET.
Resistance Check
- Set the multimeter to resistance mode.
- Connect the multimeter leads to the Drain and Source pins.
- Without applying any voltage to the Gate, the MOSFET should be "OFF", showing high resistance (ideally, it should appear as an open circuit).
?
-JJ
