simonsen: 31/1; Sweetheart and Mistaken Sweetheart
The Miniature Receiver OP-3 Type 30/1 is also often on the Internet incorrectly referred to as "The Sweetheart". It's a dual band (MW & SW) superhet. A Superhet is not at all like a TRF or Regenerative radio. The case is similar but knob layout different: The "Sweetheart" is a 3 valve TRF regenerative set.