ACARS R820T vs. FC0013

So long time a go i looked for new dongles. So i visit this Wiki:
Wiki said:
Fitipower FC0013 22 - 1100 MHz
So i ordert 10x of this Dongle for Mode-S and what happened the Dongle goes just to 900MHz...
After a long time i found them in a Box and plug in my Pc and switch to the ACARS Channels on 131MHz and the results are amazing!
I receive a little more messages with my FC0013 that with R820T !!!
I turn the to the full Gain and calibrate the Frequency Correction with the VOLMET.