RF Guru
9kW ICAS High-Power Dual-Core Band Specific 1:1 Current Balun or Choke
9kW ICAS High-Power Dual-Core Band Specific 1:1 Current Balun or Choke
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Engineered for serious HF operators, these high-power current chokes are built on stacked dual-core architecture inside a rugged polycarbonate enclosure with HV coating, custom gaskets, and a decompression valve for outdoor QRO use. Each choke is hand-assembled and verified for proper impedance across its specified range. All performance values listed below are conservative real-world figures based on measured results.
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 model is designed for high-power ICAS duty cycles, tested to withstand sustained legal-limit operation and beyond. The fully sealed build resists moisture, salt, and UV exposure, while the internal HV coating prevents corona discharge and maintains stable impedance under high voltage stress. Available with PL-259, N-type, or 7/16 DIN connectors for maximum compatibility with your station’s feedline system.
Variants
160–40 m Dual-Core Current Choke (9 kW ICAS)
Optimized for the low bands, offering deep rejection of common-mode currents on 160, 80, and 40 meters. If extended operation on 30 m is needed, an upper-HF choke can be placed in series. Supplied with your choice of PL-259, N-type, or 7/16 DIN connectors. Impedance and CMR values are conservative and verified under real QRO load conditions.
| 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 providing consistent isolation from 30 through 10 meters. Ideal as a feedline choke for multiband verticals, Yagis, or EFHWs operating above 10 MHz. Available with PL-259, N-type, or 7/16 DIN connectors. All impedance and CMR numbers are conservative and based on practical test setups.
| 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 |
When multiple chokes are installed in series, their impedances add, increasing the total common-mode isolation. Each doubling of total choking impedance provides roughly +6 dB of additional suppression — meaning two 30 dB units in series yield about 36 dB total isolation.
6 m Dual-Core Current Choke (3 kW ICAS)
Compact VHF choke engineered for 50–54 MHz operation. Provides high-frequency common-mode isolation for 6 m beams and end-fed verticals. Supplied with PL-259, N-type, or 7/16 DIN connectors for seamless integration into heavy-duty VHF installations. All figures represent conservative, verified real-world performance data.
| Band | Choking Impedance (Ω) | Common-Mode Rejection (dB) |
|---|---|---|
| 6 m (50–54 MHz) | 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 architecture for extended thermal and magnetic headroom
- High-voltage internal coating to prevent corona and arcing
- Polycarbonate housing with precision-cut silicone gaskets for IP-rated sealing
- Integrated decompression valve for pressure equalization
- Connector options: PL-259, N-type, or 7/16 DIN (field-serviceable)
- All impedance and CMR values stated are conservative, verified under load
At RF.Guru Lab, all choke measurements follow industry-standard EMC procedures. We use a calibrated test setup with two precision probes: one probe injects controlled common-mode current into the device under test, while the second probe measures the resulting common-mode current at the output.
This method directly quantifies common-mode rejection (CMR) in dB — exactly what determines a choke’s ability to suppress unwanted RF currents on coax shields.
Most “choke tests” found online use a standard VNA in differential mode. That measures only the differential impedance between inner and outer conductors — not the actual common-mode path. Our method follows the same principles used in professional EMC compliance testing, ensuring that every dB quoted reflects real common-mode suppression, not simulation artifacts.
Mini-FAQ
-
Q: Can I use the 160–40 m choke above 30 m?
— You can, but its impedance drops fast. Combine it with the 30–10 m choke in series for full HF coverage. -
Q: Are these waterproof for outdoor use?
— Yes. Each enclosure is gasket-sealed, HV-coated, and equipped with a decompression valve. -
Q: What connectors are available?
— All variants are offered with PL-259, N-type, or 7/16 DIN connectors, rated for QRO duty cycles. -
Q: What does 9 kW ICAS mean?
— It refers to Intermittent Commercial and Amateur Service: suitable for high-power contest and amplifier operation. -
Q: How accurate are the impedance numbers?
— They are deliberately conservative, based on real in-situ tests under power with standard coax geometry.
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