Toroid for use as HF/VHF balun, unun

A professional-grade core selected and tested by SOTABEAMS for 125 Watt 1:1 and 4:1 baluns; 3 - 50 MHz.

For higher power use, the cores can be stacked. These toroids are also great for combatting RFI problems.

Toroid cores are brittle so avoid banging them against hard surfaces.

Toroid core weight = 14 grams

OD = 29 mm ID = 19 mm

Equivalent to type 43 material

Typical Application

1:1 Baluns should be wound as shown in the diagram below.

Each pass through the hole in the toroid is a turn.

For 50MHz 3 + 2 turns of RG58 is recommended.

For HF 7 + 6 turns of RG174 is recommended.

Hold the ends in place with cable ties.

This diagram shows 4 + 3 turns, 4 on the left and 3 on the right.

The crossover through the centre is not counted in the left or right sets of turns. The crossover is symmetrical, so there is no particular reason to include it in one set rather than the other. But since the crossover does pass through the hole in the toroid, the total number of turns is technically 8 (4+3, and +1 for the crossover).

The exact number of turns is not critical, there just have to be enough to give sufficient common mode impedance at the lowest operating frequency.