I have been playing with the RFM22B transceivers, with MikeM s library, and it seems the raw ones I receive are set at full power, and draw 80 mA ( or try to ) from the Arduinos 3v3 supply.
It wouldnt run at all, but I put a 2,200 Mfd cap on the 3v3 to help supply the power each time it transmits, and it now runs.