I've build a stand-alone arduino which functions as an arduino pro(3,3V;8MHz) w/ Atmega328. It functions perfectly and i'm using it with a gps reciever(UP501). The UP501 has 2 input voltage pins, a backup power supply and a main power supply. The backup-power supply is connected to +3.3V and the main power supply is connected to D2. The output voltage from D2 is 3.3V as expected, but when I connected the GPS to D2 the voltage drops to around 2.7V, where I need at least 3V. The 'normal' voltage on the back up power supply does stay at 3.3V. Can anybody help me out with this?