Mike
WE0H




Mal h wrote:

Mike
The core material is usually 3C5 or similar used in old tube TV'S. I have
rewound several for both 137 and 500 kcs and they are perfect for the job.
These are the larger ones,  today they are a lot smaller in transistor tv's.
I think Stefan uses one in its original state with the high value Inductor
already on the core. They worked around 15 - 20 kcs.
So possibly an original with the high inductance would resonate a vlf long
wire antenna and wind a few turns on the opposite core side to couple to the
TX
I hope this helps
The ones that I use are square 3 inches long each side and 3/4 inch thick.

mal/g3kev