[Elecraft] BL-1 and BL1-1 Balun Questions

[Ron D'Eau Claire]

Hi David:

You asked about how to get the three turns on the BL-1 core. Three turns
means that you see TWO loops of cable going down the outside to of the core
on each side. (Remember, turns are *always* counted by the number of passes
through the center of the core). For each hole, the wire starts at one end
of the core, goes through the hole (that's turn 1), loops around the
outside, back through the same hole (turn 2), around the outside the second
(and last time) then goes back through the same hole (turn 3) one last time.
Where it starts at one end you'll strip and solder to the terminals on the
board near the coaxial input connector and where it ends at the opposite end
you'll strip and solder the wires to the terminals at the output end of the
BL1 board. 

I have a hunch you're trying to see three loops of wire around the core on
the outside: that's why it won't fit and there isn't enough wire. That would
make four turns! 

You wanted to know if you were building the 1:1 or 4:1 version. The ONLY
difference between them is how the windings are connected at the output end
of the board. If you hook the red and white leads to the circuit board pads
as shown on the board - white leads to white pads and red leads to red pads,
you'll have a 4:1 balun.

If you want a 1:1 balun, connect the two white leads together and connect
them to the pad marked WHITE nearest the edge with a number 2 on the board,
then connect the two red leads together and connect them to the pad marked
RED at the edge with the number 1 on the board. The inner "white" and "red"
pads are not used. That's the only difference between the 1:1 and 4:1
versions.

Ron AC7AC