Mark, DC3MS has completed his little PA to match his µBITx using eBay modules ( MRF186 + LPF Board ) and a NANO connected via i2c to control it.
The PA board is available on eBay from different sellers. The boards are also used in the MX-P50M. https://vk2qr.wordpress.com/2014/11/25/mx-p50m-hf-amplifier-review/
He added a tandem match from eb104.ru, 4 arduino relays for PTT and ATT (-6dB) and an optocoupler board for switching the LPFs.
The Nano is connected to the ubitx via i2c. Mark had to insert some lines of code to send the frequency and PTT info to his amplifier. It was a tight fit in Ian KD8CEC’s software, as there was not much memory left for additional code.
I tend to forget to switch antennas when changing fom 40/80m to higher bands and blew up a few finals in the past, so the code in the amplifier demands a low power tune after band changes.
When transmitting and high SWR occurs, PTT is disabled.
ATT is enabled on 20-80m as Mark’s µBITx puts out more than 5W on these bands.
Mark will gladly share all details if anybody is interested,
Link to the low pass filter used in the linear amplifier by Mark.
Reference