Personally, I would avoid using a gradient in the footer. I also suggest including a navigation bar with links to your about, legal, privacy, and contact pages.
Consider restricting the width of the primary content as well. As it is intended for technically savvy readers, aim for 16-18 words per line and boost the font size slightly.
Consider a full-width header background color as well. Take a look at how Amazon does it. Make each top level item in the main navigation connect to a new page - it's more intuitive. If I linger over Support for VNAs, I won't know which one to click until I know what those things are. However, if you removed the dropdown and linked to a help page, you could list all of the support subjects with a brief description before clicking the "read more" button.
Consider having a single help page that is separated down into topics/products. Everything appears to be dispersed among several locations. Excellent if you know where to look, but not so useful for someone who has just purchased a VNA and has no idea where to begin.