I made a 1:1 transformer with  3 turns primary and  3 turns secondary. The coil value of 3 windings of the 61 material...

Did you know that an FT140 core fits exactly in an FT240 core? FT240 - 31 with 2 x5 turns (upper picture left) FT240 - 43 with 2 x5 turns...

6 windings together and 8 windings distributed over the core Windings distributed over the core Schematic: First measurement:...

To reduce interference from man-made noise, I often use a loop antenna which is known for its ability to decrease unwanted signals. I...