I have a tv from Germany and the coax cable from my direct box will not fit on the tv

If the TV has a German TV standard tuner the output of a US DTV box through the antenna output will not be compatible. It might work if you connect if with AV cables (which ones depends on the box and TV).
 
Compatibility depends on the TV itself and whether it will support various transmission formats (other than PAL). Many years ago, I too had a German TV (massive tube type) that was multi-format. I actually still have the coax adapters I used then in a box of cables and converters at home.