Looking for a high-performance toroid ferrite core compatible with FT240-43?
This 2.4" NiZn ferrite ring is built to suppress EMI and reduce RF noise across a wide frequency range.
Perfect for HAM radio, EFHW antennas, and power transformers, it delivers consistent performance where it matters.
Whether you're building a balun or fine-tuning your feedline, this core holds its ground — and your signal.
| ▌ PRODUCT | ▌ QUALITATIVE INFO |
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> Core: NiZn Ferrite (FT240-43 Compatible) > AL: 1075 ±20% | OD: 2.4” | ID: 1.4” > Suppression Range: 20–250 MHz > Uses: RF EMI Chokes, Baluns, EFHW Antennas |
Natural Technical Content Below Table (experience + depth + FAQ):
I picked up this FT240-43-compatible ferrite core to quiet down a noisy EFHW antenna that had been giving me headaches on 40 meters. Slapped a few turns of coax through it, and the background hash dropped instantly. I won’t say it solved everything, but enough that I didn’t have to keep re-tuning the antenna every other session.
The AL value (~1075) held up as expected in my tests. Wound 10 turns for a quick-mode choke and got around 100 uH. No heating. No drift. Just clean attenuation.
Where it gets interesting is when you start stacking them. Two cores back-to-back in a high-power unun setup brought stability I hadn’t seen in previous air-wound attempts. It didn’t just reduce signal loss — the audio sounded cleaner. Hard to explain unless you've heard RFI disappear mid-transmission.
Tech-side FAQs:
Q: Can I use this core in a 100W HF transmitter setup?
A: Yes, but make sure you respect core saturation limits. One core is usually fine; for higher power, consider two.
Q: Is this suitable for DIY common-mode chokes?
A: Definitely. Works well from 20 MHz upward. I got great results using it with RG-58 and RG-316.
Q: What’s the highest frequency this core can suppress?
A: Spec sheet says up to 250 MHz for EMI, and up to 500 MHz in real-world RFI suppression cases.
Q: Does this replace FT240-43 1:1?
A: It’s compatible in size and specs. Slight variation possible in AL, but well within safe range.
Cautionary Note:
If you're experimenting with high-voltage matching transformers, this core might look similar to others — but NiZn reacts differently under sudden load changes. I had one saturate in a 300W balun test due to lack of ventilation.
Final Thought:
I keep a few of these cores on standby — not because I go through them fast, but because once they’re in a build, I never pull them out again. They just… work.
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