I won't be building these and selling them. I hate soldering up parts. If you can find the RSSI pin on your RX, you probably can build one of these. Just get a good soldering iron with a narrow tip and keep it hot. I use this adjustable heat soldering station
, but a 30 watt iron works fine if you coat the parts in soldering flux.
The explanation is provided as additional information for educational purposes and trouble shooting. If you read and understand basic logic controllers, you can figure out how to modify this for even more Rx units to increase your system reliability even more.
I will take pictures of my circuit board when I get home (I'm out of town for the week).