Comet SMA-24J (SMA-Female) vs TIDRADIO TD-771 GMRS (SMA-Female)

The TD-771 GMRS is the clear winner here. Both are flexible SMA whips, but they're designed for different purposes and excel in different roles.

The single most important differentiator is frequency coverage and electrical efficiency at intended bands. The Comet SMA-24J is a dual-band antenna optimized for VHF/UHF generalist use. At 146 MHz it's electrically short and compromised, delivering realistic performance around -0.4 dBi. At 435 MHz it performs much better at 2.9 dBi, though its claimed 3.5 dBi is somewhat optimistic. The TD-771 GMRS is purpose-built for 465 MHz GMRS operation where it achieves a realistic 3.0 dBi as a proper 5/8 wave design. Its claimed 2.15 dBi is actually conservative relative to its electrical length, which builds confidence in the manufacturer's honesty.

The Comet makes sense for operators who need VHF and UHF coverage on a single antenna and accept compromised VHF performance as the tradeoff. The TD-771 belongs on any dedicated GMRS handheld where you want legitimate 5/8 wave performance at a budget price point.

For most users, the TD-771 GMRS offers superior value: better gain at its intended frequency, realistic spec claims, and a ten dollar savings.