1.8–30MHz HF Shortwave Choke Coil Magnetic Ring | M Male Female

1.8–30MHz Shortwave Choke Coil Magnetic Ring – HF Radio Accessory

Upgrade your HF shortwave radio setup with this precision-wound Shortwave Choke Coil Magnetic Ring. Covering 1.8 to 30 MHz, this common-mode choke is engineered to suppress unwanted common-mode current, significantly reducing electromagnetic interference (EMI) in your station's feed line. Available in two core sizes — EM-25 and EM-43 — to suit a range of power levels and heat dissipation requirements.

Key Features

• Effective EMI Suppression: Suppresses common-mode current across the 1.8–30 MHz HF shortwave band, keeping your signal clean and your station quiet.
• Premium Magnetic Cores: Wound with high-quality imported magnetic ring cores for consistent and reliable performance.
• M Male-to-M Female Interface: In-line M (PL-259/SO-239) connector design allows easy series insertion between your transceiver and feed line — no adapters needed.
• Two Core Options:
  • EM-25 (Small Ring): Rated 200W, magnetic ring diameter approx. 4.5 cm — ideal for QRP and mid-power stations.
  • EM-43 (Large Ring): Rated 1000W, magnetic ring diameter approx. 6 cm — superior heat dissipation for high-power operation.
• Durable ABS Housing: Black ABS enclosure protects the wound core from physical damage and environmental exposure.

Specifications

Package Contents

• 1× Shortwave Choke Coil Magnetic Ring (EM-25 or EM-43, as selected)

Notes

Actual color may vary slightly from product images due to monitor brightness and lighting conditions. Please allow for minor measurement tolerances (±1–2 mm) in the listed dimensions.

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For general guidance on electromagnetic compatibility (EMC) and radio frequency interference, see the FCC or refer to NIST resources at NIST Electromagnetics.

Frequently Asked Questions

Q: What is a shortwave choke coil magnetic ring and what does it do?

A: A shortwave choke coil magnetic ring (also called a common-mode choke) is wound around a ferrite or similar magnetic core. When placed in series on a coaxial feed line, it presents high impedance to common-mode RF current — currents that flow on the outside of the coax shield — without affecting the differential signal passing through. This reduces EMI, improves signal purity, and helps prevent RF from entering your shack equipment.

Q: What is the difference between the EM-25 and EM-43 versions?

A: The EM-25 features a smaller magnetic ring (~4.5 cm diameter) rated for up to 200W — a great choice for QRP or moderate-power HF stations. The EM-43 uses a larger ring (~6 cm diameter) rated for up to 1000W, offering better heat dissipation and suitability for high-power HF transceivers and amplifiers.

Q: How do I install this choke coil in my radio setup?

A: Installation is straightforward thanks to the M Male-to-M Female inline connector design. Simply unplug the coaxial feed line from your radio or antenna tuner, connect the male end of the choke to the radio output, and plug your feed line into the female end. No tools or adapters are required for standard PL-259/SO-239 coaxial setups.

Q: What frequency range does this choke coil cover?

A: This choke coil is designed to operate across the HF shortwave band from 1.8 MHz to 30 MHz, covering all standard amateur HF bands (160m through 10m) as well as shortwave broadcast and measurement applications.