The v2.0 is a further evolution of the A600 design that was awarded 2nd place in the NXP Homebrew RF Design Challenge 2019.
For those familiar with the previous versions (v1.0 and v1.2), the v2.0 comes with a number of improvements:
- Improved input and output circuitry now allows 1.8 to 72Mhz coverage (slightly reduced gain and max power on the 4m band)
- Double-sided PCB with a solid ground bottom side, for optimal electrical and thermal transfer
- Redesigned bias circuit, easier to adjust
- A board cutout for power RF attennuators is present, allowing input configurations for up to 100W RF drive
- Added input drive level sense circuitry; allows for input power measurement, overdrive protection and automatic RX/TX switching to be implemented via the (now expanded) Sensor Port.
This is an Advanced level kit and assumes you have a good understanding of electronics. The PCB is supplied with the surface-mount components already installed, but some of the parts supplied in this kit will require assembly and soldering. You will also have to source a power supply and a large heatsink, drill and tap the heatsink and build your choice of input-output switching circuitry. Recommendations are included in the provided Assembly Instructions.
The Sensor Port provides sensor outputs for measuring circuit parameters such as supply voltage, supply current, heatsink temperature, forward power and reflected power, input drive power. They are all analog signals in the 0-5V range and can be easily interfaced with a microcontroller of your choice (eg: Arduino) to implement display or protection routines. The signals are described in the provided Assembly Instructions.
To use this amplifier on the air and meet legal requirements, it is recommended you use a bank of switchable Low Pass Filters and make sure you don’t overdrive it beyond the design output power.