The Trimble Thunderbolt GPSDO comes with a 75 ohm F connector even though the input is 50 ohms. In the manual, Trimble basically says that the impedance mismatch is irrelevant, the cable is low cost, easy to get, and good enough to do the job with absolutely no problem.
Ed
Sorry I do not understand your reply, I think I get the part about the impedance being irrelevant but Trimble, and cable being low cost? :-)
In North America, satellite and cable TV systems are connected to your TV with 75 ohm cable equipped with F connectors. You can buy high quality cable rated for over 2 GHz with 4 seperate shields at any home improvement store. Trimble realized that this cable would work very well to connect their 50 ohm Thunderbolt GPSDO to the antenna, so that's what they specified. They even made it easy by equipping the unit with an F connector instead of the more common BNC, N, SMA, or TNC connector.
So, if a 75 ohm cable is good enough for Trimble, it shouldn't cause you any problems. The biggest nuisance might be having a couple of adapters in the connection to convert between F connectors and whatever else you use. I don't know if F connectors are used in Denmark, but either Amazon or ebay will have whatever adapters you want.
Ed