Czech pride is never in short supply on Christmas Day at the home of John Sabol, where the longtime Seven Hills resident can often be found singing one ethnic song after another to relatives over the phone. So it made sense that the avid lecturer on local ethnic history and genealogical research, who has also authored four books chronicling local neighborhoods, would be the perfect choice to host the “New Czech Voice of Cleveland” radio show, which airs from 3 to 4 p.m. Sundays.