Diamond X-300A / X-300NA
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| Frequency | 144-148 MHz, 430-450 MHz |
| Gain | 6.5 dBi |
| Modes | FM, SSB, CW, digital |
| Connector | SO-239 (X300A) or N Female (X300NA) |
| Year | 2000 |
| feedpoint | SO-239 UHF (X300A) or Type-N Female (X300NA) |
Diamond's mid-gain dual-band base collinear: 6.5 dBi on 2m (2x5/8 wave) and 9.0 dBi on 70cm (5x5/8 wave), handling 200W with a 112 mph wind rating. It is DC grounded for lightning and static protection, with a heavy-duty fiberglass radome and overlapping shells, and is pre-tuned. It is available with SO-239 (X300A) or N (X300NA), sitting between the X50A and X700HNA.
10 feet tall (more visible than the X50A). The higher gain means a lower radiation angle, which can create coverage gaps nearby in hilly terrain. The gain figure (6.5/9.0 dB) is Diamond's rating, likely dBi, so roughly 4.4/6.9 dBd of directional gain.
A mid-gain dual-band base collinear. The X300A offers enough gain to notice an improvement over the X50A without the size and cost of the X700HNA. It is a popular mid-gain dual-band base antenna.
The Diamond X300A is the mid-tier favorite in Diamond's dual-band base antenna line — a fiberglass collinear vertical for 2 meters and 70 centimeters that strikes a popular balance between gain and manageable size. At roughly 10 feet tall it delivers about 6.5 dBi on 2 meters and 9.0 dBi on 70 centimeters, a clear step up from the compact X50A.
Like its siblings it is radialless and end-fed, needing only a mast and coax, and it handles high power well. The extra height buys more gain, which on VHF and UHF translates into a lower takeoff angle and better reach to distant repeaters, while still being short enough for a typical rooftop or chimney mount.
It is a current product and probably the most recommended all-round dual-band base antenna Diamond makes. The shorter Diamond X50A is the budget option below it, and the tall Diamond X700HNA is the high-gain flagship above.