Another interesting eBay find - The Electrad Forum

Here's another interesting find on eBay tonight... a leather bound set of 12 issues of something called "The Electrad Forum", including a 3 page article on the RCA Theremin with schematics.

The Electrad Forum (ebay)

This appears to be a periodical produced by the Electrad Corporation of America.  I couldn't find much of anything on the web about them except a couple of references to components they made around 1923/24.  I suspect this might be a document about the RCA that none of us have seen.

Anyone have more information on this company?

I'm not aware of the Electrad Forum, but John Rider is an extremely well known name in the field of radio. He was a prolific author and a publisher. Rider's service manuals are the staple of anybody who restores old American radios.