Hi Guys Here is a magazine you will need to build your own LF transmitter and also shows how to build your own LF receiver.
Radio Electronic September 1989 Pages 43 to 46 and page no. 63
archive.org/details/radio_electronics_1989-09
It was made for cw but with a added circuit you can make it transmit an audio source and you could add a pll circuit for your frequency.
Happy building and have fun Jeff
I’ve done this with a
I’ve done this with a transverter hooked into a yaesu ft817nd