My low cost amplifier has been modified yet again. I added a different filter board so that the amplifier will work from 160M through 15M. The previous version had a home brew filter board covering 80M, 40M, 30M, and 20M. Instead of re-doing the filter board to include more bands, I decided to go with the following filter board from HF Projects:
Below is an image of the filter board (right-side) and the Arduino amplifier controller (left-side):
I found that the amplifier started to loose its efficiency above 21Mhz. I also had some issues with the COR/PTT board causing self oscillation; I went with a simpler solution.
Here is the schematic of the Arduino amp controller. Note that this is work in progress:
The latest version of the Arduino amplifier controller is found here:
PTT/COR Schematic Diagram