Comet CHA-250B Review: The No Radials Vertical, and What It Costs

Eighty through six metres with no tuning and no radials, from a 23 foot vertical.

Specifications

Specifications above come from Comet's published specifications for the CHA-250B as listed by the seller. Treat pricing as approximate, since Amazon pricing moves.

What it does well

• Continuous coverage from 80 through 6 metres, including the WARC bands, with no traps to retune.
• No radial field, which makes a flat roof, a balcony or a tiny garden a viable location.
• Nothing to adjust. It goes up and it works, which is a real advantage for anyone installing at height.
• Low SWR everywhere means an internal radio tuner will be happy on every band without an external box.
• Physically unobtrusive for what it covers, at around 23 feet of thin vertical.

Where it falls short

• A broadband antenna achieves flat SWR partly through a lossy matching arrangement. Low SWR is not efficiency, and some of your power becomes heat rather than signal.
• On 80 metres it is far shorter than a quarter wave, which compounds the loss. Expect it to be beaten clearly by a full size wire.
• The 250 watt PEP rating rules out running a legal limit amplifier into it.
• A vertical has a low take off angle, which is good for distance and poor for nearby contacts on the low bands. It is not an all purpose antenna.

Low SWR is not the same as efficiency

This is the single most useful thing to understand before buying any broadband antenna. A standing wave ratio meter tells you how well the antenna system matches your feedline. It tells you nothing about how much of the power that goes in comes back out as radio waves. A resistor of the right value is a perfect match and radiates nothing at all.

Broadband verticals sit somewhere between a resonant antenna and that resistor, and where exactly depends on the band and the design. On 20 through 10 metres, where the antenna is a reasonable fraction of a wavelength, the compromise is modest. On 80 metres it is large. Use the quarter wave vertical calculator to see how long a real quarter wave on 80 metres would be, and read vertical versus dipole for HF for what take off angle means for the contacts you want.

What owners report

Published owner reviews split almost perfectly into two camps, and both are right. Owners who installed it because nothing else was possible, on a roof, in a restricted development or on a small city plot, generally report being pleased: it works on every band, needs no attention, and makes contacts they could not otherwise make. Owners who compared it directly with a resonant wire or a radial equipped trap vertical report a clear difference in favour of the wire, particularly on 40 and 80 metres.

The recurring technical observation is the one worth internalising. Several owners note that an antenna presenting a low standing wave ratio across five octaves is doing so with loss somewhere, and that a dummy load has a perfect SWR on every band. That is not a criticism of this specific antenna, it is how broadband designs work, and the manufacturer's own convenience claims are what you are buying.

Practical notes that come up often: mount it as high as you safely can, keep the feedline away from the radiator, and use a common mode choke at the feed point. Height matters more than anything else you can change. The antenna height calculator shows what raising it does, and ferrite chokes versus common mode baluns covers the choking question.

Who it suits

• Operators with no space or no permission for a radial field or a wire.
• Roof, balcony and small garden installations where footprint is the binding constraint.
• Anyone who wants all band coverage including the WARC bands with nothing to adjust.
• Stations running 100 watts or less who value never touching the antenna again.

Who should skip it

• Anyone with room for a resonant dipole or an end fed half wave. Both will outperform it for less money.
• Low band specialists chasing weak signals on 80 metres.
• Anyone planning to run an amplifier. The 250 watt rating is the ceiling.
• Operators who want strong nearby coverage on 40 and 80 metres, where a low dipole is the better shape.

Alternatives worth considering

Keep reading

• Vertical vs dipole for HF
• Best HF verticals
• Hustler 6-BTV review
• Quarter wave vertical calculator
• Antenna height calculator
• Apartment and restricted antennas

This review draws on published specifications, manufacturer figures and the consensus of verified owner reviews. We have not tested this product ourselves, and we say so rather than implying otherwise. As an Amazon Associate we earn from qualifying purchases.