I have operated a GP-7 with this type of inverter and an autotransformer. It is limited, the GP-7 could only be ran at half power (around 40 watts out). But is an option if you don't have an 800-1 or PU-43/A It is loud too! A video of it running is here: https://vimeo.com/241787116 Cheers, Dewayne