Hi Frank
The radio rejectostat transformers are not shown on that diagram, but as I mentioned the 3 pin plug would connect to the radio rejectostat unit with screened cable then into the aerial and earth sockets of the radio. On some radios there would be a 3rd socket to connect the screen of the receiver rejectostat to.
There is a link to the full details of the rejectostat system in post #41 of this recent thread on aerials
https://www.vintage-radio.net/forum/...d.php?t=157926
Mike