8051 with Xbee module

Hi,

I managed to communicate a wire antenna Xbee 2.5 with an U.FL Xbee 2.5 via micro to PC. Data is being received OK, but what I dont understand is How is the TX from the micro connected with the DIN of the Xbee is being sent at 3.3V without any voltage division or anything similar.

The thing is that the 8051 TX pin is 5V, and when ever I connected directly to the DIN of the xbee it falls down to 3.3-3.4V. How is this happening ??? All the circuits I’ve seen and Digi techniciance told me that to connect the 5V TX to the Xbee, a voltage division or voltage shifter must be used. I tried but then the Voltage will drop to 1.2V and no data will be received :x!

The received data is according to what is being sent, I tested a counter from 0 to 225 and all the ASCII characters where displayed correctly.

Another problem is that the U.FL Xbee has a cable to convert from U.FL to RSM connector, and when the Xbee is connected with the micro WITH the antenna the data stops being sent, but when I remove the antenna the data continues.

The antenna used is 2.4Ghz wifi modem, and it works when I connect the Xbee with the PC.

Any help would be great :).

Thanks

Ed