OK, what should my first proto be capable of?:

• Amplifying the output of my QRX QRP transceiver to a 70W. This QRP device can produce 5W at 16V, but things get hot if you do cw or whisper operation (which is fun, by the way). So I want to work the QRX with 12,5 Volts from a regular car battery. And the power goes down to about 2 watt. Current state is:
  
  • 12.5V = 2 Watt   (this is what I want to use in the field)
  • 13.8V = 2.7 Watt
  • 15.0V = 3.5 Watt
  • 16.0V = 4.2 Watt
  • Power is measured with a simple non calibrated dummy.
• Using class E end stage, highly efficient for only CW. Like the QRX itself. You need to push the FET's with blocks instead of nice sinusoidals to reach the high efficiency. So basically I need a amplifier gain of about 20 dB. That is quit high, but let's see how far we can come with 2W input. If it doesn't reach the full 20 dB, we can raise the input a bit, by increasing the power supply voltage. But that requires a second power supply ,....two batteries ?
• for only the 20m band, so one filter should be enough. The QRX is mono band, so we will stick to the 20m for a start. The good news is that we can start with a single filter, which make things far more easy.
• Using cheap FET's. In all literature I see negative experiences in keeping the FETs alive. So let's start with cheap ones (irf530/560)
• Excellent cooling. I want to start with a cooling block which is capable of absorbing the power needed for the 800W amplifier. This means a bit overshoot for a 100Watt amp, but I want to be able to test what the temperature is doing when I experiment with the design.
• All together I think that one battery of 12.5 Volts could be to low with the FETs, but let's see,....

So, let's move on,......