Did you know you can stop the CDH18x2´s SDI output from following the input format?

Simply connect the CDH18x2 to a PC with yello GUI running and force the device to the desired output format by forcing the parameter "output resolution". 

This way you can have a 1080i50 SDI from an 1080p50 HDMI input signal.

Please note that the CHD18x2 does not have a video scaler, so the (active) output picture will be cut or boxed into the selected format.

yelloGUI: http://www.lynx-technik.com/en/support/download-area/yellogui-software/