Quote Originally Posted by ruijc View Post
I changed modules, experiment board, etc and this only happens on the RX side.

Should it be any startup procedure sequence for the RX ?
Not sure if you mean the PIC or the transceiver. The PIC RX using HSERIN <font color=red>REQUIRES a pullup to VDD </font color>or you will get an intermittent (if at all) PIC boot. If this causes problems with the radio, you can use something to buffer the link, Tristate buffer ? I discovered this a long time back with my serial LCD project. You could "buffer" it with a simple transistor, but would then be dealing with inverted serial data.