VHF PA RD15HVF-1

Searching for appropriate additional power amplifier for my home brew VHF DRA-818 transceiver with moderate power output 15-20 watt. RD15hvf-1 is a good candidate : high gain, and capable to deliver 15 watt with 1 watt input at 12.5 VDC, is exactly match with DRA818 power output level. However, I could not find schematic for 144 Mhz application on web, most of them are designed for FM broadcasting freq band. I have to make impedance matching calculation by my self for designated frequency. Time to call my best friend Smith's Chart (Thanks to Sim Smith by AE6TY, this job never been easier ) to design input and output impedance matching network for the mosfet. Fortunately, input and output impedance table for various frequencies is well presented on datasheet, simply put the value (presented in S11 and S22 table) plot it on smith chart and obtain the L&C matching element value

Adding few more components (voltage regulator for bias circuit adjustment) and RF sensing T/R relay makes my power amplifier circuit complete ! (notice I use variable capacitor rather than fixed to allow some adjustment due to mosfet device parameter variations)