Odd behavior on my station...

Hello people, I seem to have a weird situation going on on my side right now.
The graphs shot up like crazy as soon as the temperature dropped.

The GSM(H, 2G, 3G, 4G, etc) transmitter about 500 meters from my house is also behaving oddly, shutting down at random moments.
I put up a second meter(calibrated geiger counter) and right now it fluctuates between 17 CPM and 135 CPM...

More news will follow when I got more info.

OK, so I put a new tube(Same supplier and type) in to see if it would change something. Right now it seems to be lower then the other one, I will monitor it, though.
I wonder though, could it be a faulty tube or just the end of it's life or is it something else?