steven6282:
Ok scratch that. Looks like I've got at least one bad receiver. Swapped out the receiver with my 2nd receiver and now I'm receiving messages from one end of the house to the other (about 20 meters). It was missing some signals at that range but it was picking up at least 3 in 5.
That's more like it but you shouldn't stick to that 13 cm antenna. 13 cm is for 434MHz.
The wavelength at 315 MHz is 95.2 cm so a 1/4 wavelength antenna would have to be around 24 cm.