So far, I've replaced the sensors and the new sensors are functioning properly with the OEM TPMS in the Subaru. The new sensors can also be read individually using a TPMS reset tool.
The bad news is that I've really made no progress with the hand built receiver. I've done some rudimentary work trying to read data from the sensors, but the results have been disappointing so far. The sensors will activate just fine with the TPMS tool, but I am seeing nothing as far as a data stream. The lack of reading any data so far could be the result of my lack of understanding or the fact that I bought el-cheapo radio components. US TPMS sensors typically transmit data on 315 Mhz, so it should be possible to use the receiver portion to at least see the data.. The transmitter portion is not of use since 217Mhz (I believe) is the frequency that is transmitted by the TPMS tool to activate the sensor to read data. Here is the transmitter receiver pair I bought: https://www.amazon.com/gp/prod...psc=1&pldnSite=1