Elecraft K2 Application Note

Winding T2 for Maximum Power Output on 12/10M

 by Gary Surrency, AB7MY  ( gary@elecraft.com )

For highest output on 10m/12m, it is especially important to wind T2's primary with 80-85 % of the core covered, and the secondary well spaced around the core as much as possible. Bring the secondary leads down and under the core, and then route them back to the # 3&4 pads. This allows the leads to come off of the core further apart on the core, and makes for easier connection without having the sec. leads come off the core too close together. The slightly longer lead length of T2's secondary when wound this way is not significant.

It also helps to slightly space this transformer about 1/16" off of the PCB surface to minimize any losses that may reduce the output on 10m/12m.

An image of how T2 should look when properly wound is shown here: