I decided to try my hand at building my own transmitter module. I did this mostly to save weight rather than lofting a heavy handheld radio. The Radiometrix 300mw HX1 radio seemed to be a solution that worked for many, so my brother and I bought three of them and proceeded to design the custom radio module.
I started with some simple design goals:
- Low battery voltage cutoff feature
- Interface that matches the TinyTrak
- Pre-emphasis circuit to compensate for the digital only nature of the transmitter module
- SMA output