The combination of advanced SDR designs with DSP make it possible to build a radio for any band with in the range of the SDR hardware. Band specific power amplifier modules compliment this inherent flexibility of an SDR system. One can build simple amplifiers for the band(s) of interest. With this system, multi-band operation is a simple as configuring coaxial cable connections.
The photos display power amplifiers for 144 MHz through 1296 MHz. The bands are selected by connecting the SDR and the T/R relay to the input and output coaxial connectors of the band specific power amplifier. The amplifiers are constructed from band specific MOSFET RF modules. In the case of the 144 MHz through 432 MHz the amplifiers are followed by low pass filters to reduce harmonic output. The power for each band depends on the particular MOSFET module selected for the amplifier.
A selection of RF MOSFET hybrid power amplifier modules is available: MOSFET Power Modules High quality PC board interfaces for MOSFET amplifier modules are available for purchase: Power Module Interface The copper heatsink beneath each module is visible in the interior view. This heat sink approach simplifies amplifier construction by eliminating the need for ‘fans and fins’ in the construction of these modules.