I too experience almost a complete loss of GPS and video signals after installing the Stage 3 antenna mod. The Phantom 2+ was basically only able to fly in ATTI mode.
I corrected this 100% by applying the aluminum foil mod here: https://www.youtube.com/watch?v=q31s6NDFUlA . I purchased the adhesive foil from Amazon here: http://www.amazon.com/gp/product/B000UC ... UTF8&psc=1 .
Now I always have complete video lock even at the highest monitor resolutions on my iPhone 6 Plus and have 9-11 GPS Satellites continuously.
The antenna mod is great but the weak link is the radio frequency interference susceptibility of the GPS module.
Mack
I corrected this 100% by applying the aluminum foil mod here: https://www.youtube.com/watch?v=q31s6NDFUlA . I purchased the adhesive foil from Amazon here: http://www.amazon.com/gp/product/B000UC ... UTF8&psc=1 .
Now I always have complete video lock even at the highest monitor resolutions on my iPhone 6 Plus and have 9-11 GPS Satellites continuously.
The antenna mod is great but the weak link is the radio frequency interference susceptibility of the GPS module.
Mack