Power Booster for radio?

Being a new owner of a 2720SL I have a question about the Power Booster for the radio antenae (Picture is attached). Would any one know why the red light is on all of the time? Will this drain the battery when trailer is in my garage? The dealer had said that the light will stay on ALL of the time! Can it be turned off at all?
Thanks in advance for any info some one may have.
The Tuscany Bandit.