Found this little ATmega328P + RFM95W combo on AliExpress …
Small box of 5, separate MCU board + radio chips cost £22.27 aka £5.44 each. The vendor sells a number of combinations for regional frequencies or using RFM69.
The PCB doesn’t have a link for DIO1 trace, hence the yellow wire. Took about 5 minutes to solder and three minutes to setup ABP & download using Classic LMIC and see uplinks.
Tomorrow I’m make another, add DHT11’s & a 7805 Vreg and wire them to both cars that are suffering badly from damp at present - may as well get some hard data on the problem.
To students and beginners, these modules are very entry level, the principal problem is the shortage of memory - they are cheap, good for ‘disposable’ devices or only requiring one or two simple sensors. They are not a good match for those wishing to warp time & space by rushing to an end result.