See https://www.americanradiohistory.com/Archive-Electrical-Experimenter/EE-1919-08.pdf https://www.americanradiohistory.com/Archive-Electrical-Expe... page 325

See https://www.americanradiohistory.com/Archive-Electrical-Experimenter/EE-1919-08.pdf https://www.americanradiohistory.com/Archive-Electrical-Expe... page 325 and 360. Couple of sewing needles across a carbon block. He noticed that when he removed the dry battery, he got a better signal. These are things that would have been available to just about anybody at the time he did his experiments.