Another way NFETs can be destroyed is exceeding Vgs limits (voltage from gate to source).
This could be due to a long source lead to ground, or a poor ground plane.
This could be due to capacitance from the drain to the gate yanking the gate around
when the drain zips up and down some 24 volts, if the gate is not being driven by a source of low enough impedance.
An NFET designed for RF makes things easier because:
1)? The source lead is often connected to the heat sink tab, which is handy because we usually want to ground the source.
?On the IRF510, it is the drain that is connected to the heat sink tab.
2) An RF NFET is designed to have lower internal capacitances, making the gate easier to drive.
3) AN RF NFET comes with app notes describing a recommended design for an RF amp.
The IRF510 was meant for blinking automotive turn signals, does not have an app note for operation at 30 mHz.
Even when following app notes describing a well thought out design,
building an RF amp that works well can be tricky.
Jerry, KE7ER
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On Thu, Aug 11, 2022 at 07:11 AM, Jerry Gaffke wrote:
I'd be more worried about shorts at the antenna, as it is excessive current (and subsequent heating) that will destroy the IRF510's.
