I programmed my UV-5RA using a Macintosh (running Mavericks, OS X (10.9.5), an FDTI cable from Amazon, and Chirp 0.4.1 but I cannot transmit. I can reach the local repeater, but if I transmit for more than a fraction of a second the radio's screen goes black, and I have to turn it off and on again to do anything. The battery is fully charged, and I have tried with three different antennas -- same result. Help !

 thanks  

    John KG6VK