Hi
thanks for the replies.
Larry the serial number of the um200c is 872. Is block 27 and I´m pretty sure it is not the antennas since I used the kit many times with the same antennas and I did not have any problem until now. The RF readings when the transmitter is 1 feet apart from the receiver is in between 10uV and 100uV and the signal start to drop maybe when the unit is 15 feet apart from the receiver.
greetings
sebastian