Winding the cores

 

This is a commercial transformer. The picture is easier to see than mine. They wrapped the cores to the outside. I put my winding through the centers. I do not think there is much difference in the final transformer. Each pass through the core is one turn. I fold my wire into a hair pin and pass through both sides at once . This is 2 turns. Pushing the ends around to where they started make a primary of 4 turns. Then using a wire twice as long as the first I fold it and put a few twist in the bend, this forms the center tap for the secondary. Passing each end through produces the first 2 turns. Put the center tap on the opposite side as the primary leads. Now make 3 more passes with each end. This produces a transformer with 4 turn primary and center tapped 8 turn secondary.

They used color coded wire which could help avoid confusion. Winding 1 coil at a time helps prevent confusion too. You need 2 of these to make a DBM.

2 transformers, four diodes and a local oscillator will make a receiver. The IF will be audio in a direct conversion receiver. 2 mixers and an IF section will produce a double conversion set. Fun to play with and easy to make.