Toroid 2643251002
Ferrite Toroid, type 43 material. This model of toroid has been found by various hams to be a good choice for ununs for EFHW antennas, for an average power of up to about 40-50W.
For QRP use, you might like to consider a 2643625002 toroid instead (smaller, lighter and cheaper than this toroid).
Outside Diameter= 1.54 in / 39.1 mm +/- 0.75 mm
Inside Diameter = 0.66 in / 16.75 mm +/- 0.50 mm
Height = 0.875 in / 22.2 mm +/- 0.80 mm
References:
- "Building an UNUN for an EFHW Antenna" article by Mike Dunstan G8GYW, in Practical Wireless October 2023
- https://owenduffy.net/blog/?p=21901 , https://owenduffy.net/blog/?p=23089 , plus various other articles that can be found by searching for 2643251002 on Owen's website
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2643251002 Toroid
90% efficient for end fed halfwave antenna tested with a Nano VNA & Rig Expert.
