Reading your original post again and your reply on this Mystery H/B Transmitter seems to fill in the missing information. Since the Silent Key was a well known radio dealer, he probably did have access to many radio equipment manufacture's schematic designs. Then took what he wanted from each design incorporating all into his H/B package. This would have been very clever

on his part since he was
not manufacturing multiple units for sale on the market.
In the past, many manufactures would purchase the competition's product through their network of sales channels. Then their sales personnel would bring the units with schematics back the company for their product development engineers to review and studying what they were interested in but
not copying for patent reasons being the Greenback
$$$$$$$ Dollars to the company that holds the patent and/or Lawsuits. And then incorporating their own circuit designs.
Many of the early Amateur Radio designs were incorporated into commercially manufactured radio equipment being for the Amateur and/or Commercial Land Mobile Radio Markets. This still exist today but mostly in the written Software code languages. And "IF" the corporation is big enough, with deep financial pockets, they"ll buy out the competition taking what they want, down sizing the development personnel and outsouring to a third world country.
