this time I tried to receive a weatherballon next to my locator. As you can see: the signal was very strong. It lasts about one and half hour, I guess.
Unfortunaly the sound cuts off in a fews seconds. This wasn't a problem of my setup. It was a problem of AutoscreenRecorder software :( .
Afterwards I deocded the signal of the transmission. Here's the result:
The baloon rises more then 31km at that day.