renaming grid and turning on battery didnt help ...

next time i will try merge it to my rover ...

Yeah, I encountered this with a battery I salvaged from the capsule.
I was carrying it back to the rover, and KA-BOOM!!!
Detonation killed me, and I nearly sh*t myself IRL, lol!

Maybe not a bug, but a feature (channels my inner Todd Howard).

If you want to keep parts from the unknown signals you need to make sure they end up being a different grid from the unknown signal, otherwise they will currently explode when the timer would have ended.

One easy way to do this in this scenario would be to use detach mode with your grinder (hold Ctrl while grinding the block you want to detach).

The grid that has more blocks when spliting up will be the one with the timer (and the explosion) attached.

It seems to me that the grid is scripted to explode after a time, because I had this happen to just armor blocks left behind as well, after I recovered the thruster. Use detatch mode with the grinder to pop the thruster off the grid, it should survive then.

I started to play SE just a few days ago, but I read up on several things, and maybe I can offer some insight. Unknown Signal is not inclusive content of the Scrapyard. It happens to solo campaigns also, to me it seems to be a top-up content from the game itself. That grid has the original intent to be dismissed if not reached in time - by the timed destruction. Therefore it is "not a bug, but a feature".
Starting a new game it show the actual timer starting from T-15min. Saving the game and reloading in this 15 min will actually miss the timer info, but the script works on, so it will explode at original T-0:00.

So if I'm correct about the above, it is incorrect to call it a bug. It is not. However the Unknown Signals are also not intended content to this map AFAIK. Therefore take caution when considering to use materials from truly unknown sources :)

Not a bug, but they are also somewhat intended to be a part of the Scrapyard. They are quite easy to deactivate as a mod setting, but that wasn't done.

As for keeping them after the timer runs out, you need to attach them to a larger grid via merge blocks or weld plates so that they lose their temporary flag that detonates them.