Hy-Gain TH-3 Jr. / TH-3MK4
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| Frequency | 20m: 14.0-14.35 MHz, 15m: 21.0-21.45 MHz, 10m: 28.0-29.7 MHz |
| Bands | 20m, 15m, 10m |
| Gain | 8 dBi |
| Modes | SSB, CW, AM, FM, digital |
| Connector | SO-239 |
| Year | 1972 |
| feedpoint | SO-239 |
Hy-Gain's smallest tribander. 3 elements on a 12-foot boom. Compact enough for rooftop or lightweight tower installations. Can be rotated with a heavy-duty TV rotator. 4-piece boom for DXpedition portability. Model variants: TH-3JRS (600W) and TH-3MK4 (1500W).
Gain is modest (5.8 dBd), short boom limits performance. Trapped design has losses. 600W limit on TH-3JRS (TH-3MK4 handles 1500W). Performance is a step down from the Explorer 14.
The Yagi for people who cannot put up a tower. A TH-3 Jr. on a roof tripod at 30 feet gets you on the air with gain and directivity for less money and less drama than any alternative. Not the best antenna; the most practical one.
The Hy-Gain TH-3JR is the compact, lightweight tri-band HF beam in Hy-Gain's lineup, a three-element Yagi for 10, 15, and 20 meters sized for operators who want directional gain without a huge, heavy antenna. The 'JR' marks it as the junior version of the larger Thunderbird tribanders, with a shorter boom and lighter weight that a modest rotator and mast can handle.
It gives up some gain and front-to-back performance compared with bigger beams, but in exchange it is far easier to put up and turn, a sensible trade for a first HF beam or a space-limited station. It uses traps to cover the three bands on one boom and handles high power. For many hams it is the entry point into directional HF operation.
Hy-Gain's parent MFJ Enterprises wound down manufacturing in 2024, and the Hy-Gain brand was acquired by ITU Corporation in 2026, so availability has recently been in transition. The larger four-element Explorer-14 is the step up in the same family, and the Hy-Gain Thunderbird is the full-size classic tribander.