I wan't to build a filter I can use with the uBITX. However, I don't want to build a filter that is strictly tied to the uBITX.
So I'm building a standalone Low Pass Filter box that will work as an add on filter for the uBITX as well as become a general purpose piece of Ham equipment I can use over and over for other needs.
It uses an Arduino to measure the frequency you're transmitting on and select any individual or combination of filters you like. The proposed design uses a set of filters and a relay switch board; such as to ones by QRP Labs. But, the Sketch code should be easy enough to modify for whatever you like.
The controller can show he selected filter with LEDs or with an optional LCD display, and show the transmit frequency as well.
I'll need to order parts and build mine to finalize the design. However, I built and tested a prototype with a signal generator.
I'm releasing the preliminary design to everyone now because it is complete enough for people to try out on their own filter designs. It makes using outboard filters really easy, and I think people will like it. I welcome feedback on improvements people make while building their own "Auto Filters" with the controller.
The code for the controller is here: https://github.com/mountaintom/TX_Auto_Filter