Ferrite Toroid FT290-43

A larger-than-life FT290 (2.9", 73mm diameter) ferrite.  Can be used for baluns/chokes that use thick coax such as RG58/RG142 or simply for more choking - cores can be stacked.  This size is only available in a 43-mix and is more than enough for UK legal power.

8-turns of RG8mini/RG58/RG316 (400w SSB) or RG142 (1500W CW/Digi) make a great "resistive" balun/choke for 5-30MHz.  If you operate on 160m or 80m, consider using an FT240-31 or FT240-75 for increased choking impedance.  We also sell the usual 2.4" versions in 31-mix (1.8-30MHz), 43-mix (5-30MHz), 61-mix (UnUns) and 75-mix (VLF).

We use three of these cores in our 1kW End-Fed Coupler.

• Use: 5-30MHz
• Size: 73.6x38.8x12.7mm, 2.9x1.53x0.5in
• Fair-Rite 5943011101 , 43-mix material

Need help choosing a ferrite?  See our page on selecting the best size/type here.

Toroid sizes/types are easy to ID, the "290" translates to 2.9" (diameter) and the "43" is the ferrite mixture. What type do you need? 43 is good from 5MHz and up (and a good general-purpose 5-30MHz solution) while 31 is good for lower HF bands. Remember, you can stack the cores for increased choking and power-handling. As always, ratings need to factor in the aerial (SWR) match and duty-cycle.

Our own legal-limit baluns and chokes use an FT240 31-mix core.