Ciao ragazzi,
un gentilissimo ragazzo Austriaco, conosciuto su un forum mi ha preparato una esaurientissima guida per modificare la mia Fx18 e trasformarla 2.4Ghz
Quindi lo ringrazio pubblicamente, si chiama
Gregor Nebel 
Here is a short documentation of what Ive did to upgrade my FX18 to 2.4GHz.
Used parts:
FrSky V8HT 2.4Ghz DIY Module:
Any
Duo-LED for indicating which mode you use (optional):
Any
ON/ON or
ON/OFF/ON switch:
I used only ON/ON as there is no need for me to turn off the transmission (might be useful for a RC Simulator):
Modification:
The following pictures should give an idea of what Ive did:
On those two pictures you can see the switch to toggle between 35MHz (green) and 2.4GHz (red).
The small button and LED in the middle (within the FX-18 logo) is the bind/indication module (also called extend board). I only drilled two holes and fixed the module by using hot glue.
The DIY module is just fixed on the center PCB, therefor use a zip tie or something simular.
On the next picture you can see the PPM signal wire (in my case yellow, but please refer to the FrSky manual for that). You need to solder this cable to the PPM pin on the FX-18 PCB. Ive secured this wire additionally with hot glue.
To have a better view where to solder the PPM signal here is another picture (thenext picsare taken from another modification guide).
The next thing would be to battery power supply line (red circle).
