It’s definitely not the dummy load, it does it on an antenna aswell.

If the swrs not changing then the load is fine. Also I think putting the heatsink in water rules out that as an issue too.

Could be you have a fake transistor?

Albert H wrote: ↑Tue Aug 23, 2022 3:40 am The heatsink is too small, and the dummy load isn't up to the job.

Iv just measured the depth of the heatsink aswell. 4cm. It looks small in the picture but it’s the same one that is recommended by enigma. Also I bought everything from enigma minus the smoothing caps, binocular ferrite and air coils.

jvok wrote: ↑Tue Aug 23, 2022 12:10 pm If the swrs not changing then the load is fine. Also I think putting the heatsink in water rules out that as an issue too.

Could be you have a fake transistor?

I really hope not, it came from enigma which i always buy from if I need real parts that will 100% work first time.

I agree. I think you can rule out a fake, if it came from Enigma. The heatsink itself, as jvok said, is probably ruled out by water cooling it. That doesn’t necessarily mean that the FET isn’t overheating; it’s conceivable that there could be an issue conducting the heat from the device to the heatsink. You need to make sure the device itself isn’t overheating; unless you’ve already ruled that out.

What you could try is running the amp until the power starts to drop, turning it off, then IMMEDIATELY taking a temperature measurement with a thermometer directly on the metal flange (not on the ceramic body and not the screw heads). Make sure you've turned the power off before you touch it!

Also do you have a link to where you got the ferrite cores from?

What voltage is your power supply

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