Your best chance may be to look up each brand name and look up their identifying features. For instance, I found this article about identifying Silvertone radios.
Part of the problem is that I can't always see the model number
or manufacturer. Supposedly, that information might be stamped on the tubes, but that requires opening it up and I'm afraid if I ask to do it, I'll something up and be stuck with it.
Thanks for sharing those links. Maybe I should change up my strategy and focus on one or two specific types rather than "all antiques" which is overwhelming.