Dino - thanks so much. I'm looking forward to buttoning it up also - this has been a long-haul build - I began in ernest last fall. I'm putting up a hex and when Bill puts one up am I certain we can get a QSO. 73-Dean
Since I have a tendency to blow-up power MOSFETs, I've shied away from the expensive RD15Hxx. When I hear that fizzle-pop-poof, I want to know I've only smoked fifty cents rather than fifteen dollars. I don't think you mentioned the Vdd of the power amp, but I assume it's 12/13.8V? Have you tried a higher voltage? Something around 24V, though you may need to readjust the gate bias, and maybe even need a small brushless pancake fan under the heat sink (I have a sub-junque-box full of them). Others using the RD15s are getting higher power from a push-pull pair by boosting the Vds. --Todd K7TFC
Hi Todd - The RD15 is designed as 12.5V device. It is not meant to be a high voltage device like the IRF switching transistors. At 13.8V it is almost impossible to burn up. I have not tried running at higher voltage since the max Vdss is 30V and ideally you want to run no more than 50% of that for safety margin. If you run it at 24V I would think you would risk blowing it up. The advantage of the RD transistors over the IRF line is they are designed for RF and have much better operating curves for RF amplification purposes.
Looks very nice and I look forward to hearing more about the build and testing during our next VWS Makers Group meeting.
Great work Dean, look forward to seeing it all buttoned up...maybe you'll get a QSO with Bill at his southern command post! 73 - Dino KLØS
Dino - thanks so much. I'm looking forward to buttoning it up also - this has been a long-haul build - I began in ernest last fall. I'm putting up a hex and when Bill puts one up am I certain we can get a QSO. 73-Dean
Since I have a tendency to blow-up power MOSFETs, I've shied away from the expensive RD15Hxx. When I hear that fizzle-pop-poof, I want to know I've only smoked fifty cents rather than fifteen dollars.
I don't think you mentioned the Vdd of the power amp, but I assume it's 12/13.8V? Have you tried a higher voltage? Something around 24V, though you may need to readjust the gate bias, and maybe even need a small brushless pancake fan under the heat sink (I have a sub-junque-box full of them). Others using the RD15s are getting higher power from a push-pull pair by boosting the Vds. --Todd K7TFC
Hi Todd - The RD15 is designed as 12.5V device. It is not meant to be a high voltage device like the IRF switching transistors. At 13.8V it is almost impossible to burn up. I have not tried running at higher voltage since the max Vdss is 30V and ideally you want to run no more than 50% of that for safety margin. If you run it at 24V I would think you would risk blowing it up. The advantage of the RD transistors over the IRF line is they are designed for RF and have much better operating curves for RF amplification purposes.