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RF Guru

9kW High Power Dual Core 1:1 Balun for Wire Antennas

9kW High Power Dual Core 1:1 Balun for Wire Antennas

€206,00 EUR
€206,00 EUR
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Connector
Complementary: Stainless Steel (RVS / INOX 316) Mounting Kit available — use the small version for this choke.
All our products are handmade, and fulfilment times may vary depending on order volume. Please allow 2–3 weeks for your order to be completed and shipped.

Designed for wire antennas such as dipoles, inverted-V configurations, this high-power current choke provides stable, high-impedance isolation between the radiating wire and the feedline. It features a single coax connector (PL-259 or N-type) and two stainless steel M6 terminals for direct wire attachment, plus dual INOX eye bolts for mechanical strain relief. The housing is fully sealed and ready for permanent outdoor use.

Related reading:
Baluns in a Nutshell
Why “Common-Mode” Is the Most Abused Term in Ham Radio
How Much Choking Do You Really Need — for RX and TX?

Built for the Long Run

Each choke is rated for high-power ICAS duty cycles, tested beyond legal-limit operation. The polycarbonate enclosure with HV coating, custom silicone gaskets, and decompression valve ensures reliable service under moisture, salt, and UV exposure. Internal high-voltage coating prevents corona discharge and maintains impedance even at elevated voltages. Choose between PL-259 or N-type coax input connectors.

Variants

160–40 m Dual-Core Current Choke (9 kW ICAS)

Optimized for low-band wire antennas. Offers deep rejection of common-mode currents on 160, 80, and 40 m. For extended upper-HF operation (30 m and above), combine in series with the 30–10 m choke. Features PL-259 or N-type coax input and dual M6 stainless terminals for wire connection. All values are conservative, verified under load.

Band Choking Impedance (Ω) Common-Mode Rejection (dB)
160 m 4.0 kΩ 44.1 dB
80 m 8.0 kΩ 50.1 dB
40 m 2.0 kΩ 38.2 dB
Approx. 0.5 kΩ → 26.4 dB on 30 m. Add a 30-10M choke in series for ≈ 3.5 kΩ / 43 dB.

30–10 m Dual-Core Current Choke (5 kW ICAS)

Broad upper-HF design, ideal for EFHW, multiband dipole, and OCF configurations operating above 10 MHz. Equipped with PL-259 or N-type input and dual M6 stainless wire posts. All impedance and CMR figures are conservative, verified under load.

Band Choking Impedance (Ω) Common‑Mode Rejection (dB)
30 m 1.90 kΩ 37.6 dB
20 m 1.25 kΩ 34.0 dB
17 m 1.30 kΩ 34.3 dB
15 m 1.25 kΩ 34.0 dB
12 m 1.10 kΩ 32.9 dB
10 m 1.00 kΩ 32.0 dB

Maximum ICAS/CCS Power Ratings

Connector Type 160–40 m Band 30–10 m Band 6–2 m Band Limiting Factor
PL-259 / UHF ≈ 2.7 kW ICAS ≈ 1.3 kW ICAS ≈ 0.6 kW ICAS Connector
Type-N ≈ 10 kW ICAS ≈ 5 kW ICAS ≈ 2 kW ICAS Coax
7/16 DIN ≈ 10 kW ICAS ≈ 5 kW ICAS ≈ 2 kW ICAS Coax

Construction Highlights

  • Dual-core ferrite architecture for extended thermal & magnetic headroom
  • High-voltage internal coating prevents corona and arcing
  • Polycarbonate housing with precision-cut silicone gaskets for IP-rated sealing
  • Integrated decompression valve for pressure equalization
  • Single PL-259 or N-type input + dual M6 stainless terminals for wire outputs
  • Two INOX 316 eye bolts for mechanical strain relief and hanging
  • All impedance and CMR values are verified under power in real antenna setups
Technical Validation — How We Measure It
At RF.Guru Lab, each choke is tested using standardized EMC common-mode procedures. A calibrated dual-probe setup injects a known common-mode current and measures the resulting suppression directly in dB.

This approach quantifies real common-mode rejection (CMR) — not just differential impedance between conductors. It reflects how effectively the choke blocks RF on the coax shield and antenna feed interface.

Most ham tests use VNAs in differential mode, which does not capture the true common-mode path. Our method mirrors professional EMC compliance testing for accurate real-world values.

Mini-FAQ

  • Q: Can I use the 160–40 m choke on higher bands?
    — Yes, but impedance drops above 30 m. Add the 30–10 m choke in series for full HF coverage.
  • Q: Is it weatherproof for permanent outdoor installation?
    — Absolutely. Each unit is sealed with gaskets, HV-coated, and vented through a decompression valve.
  • Q: What connections does it use?
    — A single PL-259 or N-type input for coax and two M6 stainless wire terminals for antenna connection, plus eye bolts for strain relief.
  • Q: What does 9 kW ICAS mean?
    — It denotes Intermittent Commercial and Amateur Service — suitable for legal-limit amplifier use and contesting.
  • Q: How accurate are the impedance values?
    — They’re deliberately conservative and verified under power using real-world fixtures and feedline geometry.

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Written by Joeri Van Dooren, ON6URE — RF engineer, antenna designer, and founder of RF.Guru, specializing in high-performance HF/VHF antennas and RF components.
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