R9 390 HDMI to Coax Problem

Hi,
I have a trouble streaming direct HDMI output to TV sets, I use HDMI QAM Modulator and RF slitter. The encoding is H.264 and resolution is 1080p@60, with R9 I have Black screen, I tried with NVidia GTX1060 and 1080 - works fine. I don't know what the problem - R9 is very powerful, maybe there are some problems with drivers?
Thank you!
 
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