Why Your Hexbeam Gets Louder Without a Choke (And Why That's Bad)

More Power Without a Choke? Think Again.

Many hams report that their Hexbeam appears to radiate better when no choke is used. The power output goes up. The tuner is happy. All seems fine.

But that bump in output isn't a performance boost. It's a warning sign.

Hexbeam Geometry: A Recipe for Capacitance

Unlike a full-size Yagi, the Hexbeam has bent, shortened elements. Electrically, these exhibit capacitive reactance. The result? Your transceiver sees a load with negative reactance, often far from the ideal 50 ohm resistive load.

Modern rigs with LD-MOS finals don't like that. They reduce output to protect the finals, or they distort.

So why does the power increase when you remove the choke?

The Coax Became the Antenna

Without a choke, your coax shield carries common-mode current. The feedline starts to radiate. That changes the electrical length and impedance seen at the feedpoint. Often, this masks the capacitive nature of the antenna and creates a load that the radio finds easier to drive.

The SWR might improve. The rig might deliver more power.

But that doesn’t mean your Hexbeam is more efficient. It just means you're now radiating from the coax. Some of that energy ends up back in your shack. Some ends up on your neighbours speakers. And worst of all, your antenna pattern is now a mess.

What a Choke Really Does

  • It forces the feedline to stop radiating.
  • It isolates the antenna electrically from the coax.
  • It reveals the true impedance of the antenna system.

The price? Maybe your output power dips slightly. Maybe the TransMatch (tuner) has to work harder. But your signal goes where it's supposed to: into the air, not into your shack.

Conclusion: Power Output Isn’t Everything

Don't be fooled by the wattmeter. Real performance is measured in signal reports, noise floors, and clean patterns.

If your Hexbeam "works better" without a choke, you're not improving efficiency. You're turning your coax into an unintended radiator.

And that's not ham radio excellence. That's just accidental broadcasting.

 

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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.