Checked out the SWM LNB installation video here http://www.solidsignal.com/prod_display.asp?prod=SWM-PI#MORE and it mentions that there are 2 different power inserters. A 29v for the standalone SWM, and a 21v for the SWM LNB. Is there really much of a difference? My SWM LNB came with a 29v power inserter. Where can you purchase the 21v power inserter (Mine needs to be replaced)?