Sorry that should be 830 mw max dissipation on the bs180 to-92
Dave
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--- In QRPLabs@..., "Paul KE7HR" <ke7hr@...> wrote:
My U2 was putting just over 12 volts peak to peak into 50 ohms on 80 meters using a 5 volt final drive (LM2596 switching regulator) with one final. I installed the other two finals and only got an increase of 1 volt peak to peak (about 60 mW increase). I put the full battery voltage to the finals (12.6 volts) and now get just over 30 volts peak to peak or about 2.25 watts. Since the BS170 is only rated at 350 mW I will next start cutting down the voltage to the finals with another regulator to get the power down to about 1 watt.
What are others with the three finals running for voltages?
I have run a couple of nights with the 12 volts final voltage on WSPR with the devices touching a nice big piece of aluminum. A better, field portable, type of heat sink will be worked out... For other modes with 100% transmit, I would really not recommend pushing the devices this hard.
Screen shots from the oscilloscope of the voltages into 50 ohms in the photos section.
KE7HR
