Re: Using IRF530 outputs and 2N3553 drivers in ubitx

Richie Chambless
 

I have used the Minipa 70 in my scratch built BitX. While I can get 70 Watts out (13.8v supply), it is short lived as a final will blow within a few seconds and short closed. 50 Watts will work for short QSOs, but taking for more than four or five seconds will destroy the IRF530s. My heat sink is 6”x4” with 2” fins, so I don’t think heat dissipation is the issue. 25 Watts gives me no issues, however. 

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