The APA is for provisioning only, you can use one of several sat meters to check signal strength. The APA is merely a band pass filter that isolates your assigned beam channel from the others so the modem can be "taught" which one to look for when the APA is removed. ther reason for this is that there are many areas where beams overlap and it is possible to "see" more than one. After the initial provisioning, you no longer need an APA, because the modem knows which signals to read and which ones to ignore.
However, be confident about what you are doing, because WB does not condone it, and you will most likely be charged for another installation if you mess it up.