600 Watt HF Amplifier

  Amplifier Description

There's an old axiom in amateur radio which states "Life's too short for QRP." While I generally disagree, it certainly appears to be true for 75m AM operation here in central North America, where a one watt carrier can quickly become buried in QRN & QRM. This amplifier is a mate for the QRP 75m AM Transceiver described elsewhere at this site.

The amplifier uses four Motorola MRF150 50 volt TMOS power FETs configured in push-pull/parallel and biased for class AB linear operation. This scheme yields a power gain of 20db. The 1 watt drive from the "Wheat Box" will produce a 100 watt carrier (400 watts PEP @100% modulation) with headroom to spare.

There's little original design here. The basic 2-30MHz PA brick is straight from Motorola's application note EB104. The power supply, low-pass output filter, control circuitry and instrumentation are mine. Still, I would describe this project as mostly an excercise in packaging.

  Some Amplifier Highlights

eb104  The EB104 Circuit Board

      

  Data Sheets

These documents are viewable with Acrobat Reader.
 Return to Amateur Radio
 Return to George's Place

Let's talk about Homebrew Radios!