This is intended to be a listing of various amateur-friendly RF labs, and their equipment, open to amateur use or otherwise available for borrow or rent. The owner of the lab or equipment may or may not also be willing to help, or may require use of their equipment only with supervision - you should ask! COVID restrictions may make it even harder.
The exact details are out of scope for this directory, but when you approach one of the hams or labs listed here, I suggest you know exactly what you want to test, even if not exactly how to test it. Ham radio is about learning and experimentation, and the people who have listed themselves here are willing to help - just be respectful of their time.
Equipment owners that are willing to be contacted by amateurs in need of some quick testing, please visit pull request https://github.com/tarxvftech/rflabs to add yourself to the listing; or, email me and I’m happy to do it for you ( rflabs at tarxvf dot tech ).
Note: Makerspaces may be listed here, but ideally only if they have day passes or some other ad-hoc use of their RF equipment without a full membership.
Members-only makerspaces are best found at https://wiki.hackerspaces.org/Hackerspaces
As for how to use RF test equipment - start here: https://www.ab4oj.com/test/main.html