Thanks for your reply. The inverter I purchased is indeed MSW. I am returning it. I found another and this is what the description says
"Building on the success of the PROwatt modified sine-wave inverters, the new PROwatt SW series is now capable of providing cost effective, true sine-wave output. The PROwatt SW provides household AC power anywhere. Featuring dual GFCI outlets and USB port, the compact, easy-to-use and easy-to-install design of the PROwatt SW series makes it ideal for use in all RVs. Powers all types of electrical loads including audio visual systems, variable speed power tools, rechargeable devices and convenience electronics."
Do you think this one would do the trick?
I really appreciate your help.