After modding the antenna on my taranis im getting a very high SWR value.....anyone knows why?

What is SWR: https://en.wikipedia.org/wiki/Standing_wave_ratio

I've done this mod on a few different Taranis. Tested with about a dozen different antenna. A few antennas I get 0-1 SWR. Others I get 0-7 SWR. A few others I get 1-7 SWR. And one gives me 14-17 SWR. It's not always the soldering job but also could be the antenna. All antennae used were FrSky 5 dBi and 7 dBi from Aloft Hobbies and Ready Made RC.

Grounding can also be an issue or cold solder joint. What you ate looking at is rf signal bounce it is being reflected some place. You can ohm the cable to see if it is getting interference but you need a spektrum analyzer to pin point where. Most of the time putting in a new cable fixes it because you do it better the second time.

Maybe redo it with some RG316 cable

I did this mod for the second time now. The swr is 17 with a 5db antenna. The best is to not worry about the swr and instead do a range test to ensure good reception