Hi

just finished a project using radiometrix transmitters and receivers.

You must make sure that the TX enable pin jumps to 5V before transmission. Also know that if one transmitter is sending data the other transmitter must not be active. I have noticed that the receivers does not like more than one carrier wave to be present.

Also remember to send a pre-ample. This is 55H to sync/wakeup the receiver. Send the pre-ample three times and the the data three times. This is also usefull for data validation.

Try keeping the distance from the antenna to the TXout as short as possible and keep the antenna away from any osc/toggling points on the PCB

good luck