Overall Summary: The D44H11 NPN and D45H11 PNP Bipolar Power Transistors are economically priced (Farnell etc). The NPN version appears to have useful attributes for RFPA operation at 3.7 MHz (center of 80 meter band). Unfortunately it is not well characterized in terms of specifications so some experimentation will be needed. Based on a collector current rating of IC = 10 Amps and VCE = 60 V it should be capable of producing 10 Watts PEP from a 12 V DC supply.
 | DC current gain hFE = 140 at a collector current IC = 1 Amps and fairly consistent from IC = 10 mA to IC = 6 Amps (100 < hFE < 140) suggesting good linearity potential. |
| The Transition Frequency FT = 50 MHz at IC = 0.5 Amps suggest reasonable power gain potential at 3.7 MHz. |
| The collector-emitter saturation voltage is also low (VCE,sat = 150 mV at IC = 5 Amps) suggesting good DC to RF power conversion efficiency potential. |
| The charge storage time is somewhat high at ts = 500 ns. The half cycle period of a 3.7 MHz sine wave is 135 ns. This may seem to represent a disaster but this will be best determined by actual experiment! |
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