Recommendation
For a 100-foot run that must tolerate sun, rain and direct burial, Messi & Paoloni ExtraFlex Bury 10 is the strongest documented fit among the models compared. For an exposed run with bends or an antenna rotator, UltraFlex 10 is another low-loss option, but its standard PVC version should not be directly buried. ABR400-UF remains a flexible alternative with higher published attenuation. [1–4]
For HF, the loss differences are modest. At 28 MHz, the estimated ABR400-UF loss is 0.77 dB versus 0.61 dB for UltraFlex 10, 0.58 dB for ExtraFlex Bury 10 and 0.65 dB for standard LMR-400. From 100 W input, roughly 84 to 88 W reaches a matched load before connector losses. Jacket suitability, routing and termination quality are therefore central purchase considerations.
Models and comparison scope
| Cable | Construction and intended comparison |
|---|---|
| ABR400-UF 25400F | 0.405 in; 19-strand copper center; black PE jacket. Flexible ABR reference. [1] |
| M&P UltraFlex 10 | 10.3 mm; stranded copper center; UV-resistant black PVC. Flexible above-ground alternative. [2,4] |
| M&P ExtraFlex Bury 10 | 10.3 mm; stranded center; UV-shielded PE jacket. Burial alternative. [3] |
| Times Microwave LMR-400 | 0.405 in; solid center; PE jacket. Similar-diameter fixed-run loss benchmark. [5,6] |
All results refer to 100 ft (30.48 m) of matched, new cable. They are specification comparisons, not independent laboratory measurements. The ABR figures are at 25°C; M&P figures are at 20°C. The small M&P versus LMR-400 differences should not be treated as guaranteed field advantages.
Loss across HF frequencies
The enlarged graph covers 3 to 30 MHz on a linear frequency scale. Distinct line styles, larger text and a narrow loss scale make the small HF differences visible.
| MHz | ABR400 UF* | UltraFlex 10 | ExtraFlex Bury 10 | LMR 400 |
|---|---|---|---|---|
| 3.5 | 0.27 | 0.30 | 0.27 | 0.23 |
| 7 | 0.39 | 0.37 | 0.30 | 0.33 |
| 10 | 0.46 | 0.40 | 0.37 | 0.39 |
| 14 | 0.55 | 0.46 | 0.43 | 0.46 |
| 18.1 | 0.62 | 0.51 | 0.48 | 0.52 |
| 21 | 0.67 | 0.55 | 0.52 | 0.57 |
| 24.9 | 0.73 | 0.58 | 0.55 | 0.62 |
| 28 | 0.77 | 0.61 | 0.58 | 0.65 |
Loss in dB per 100 ft. *ABR estimates use 0.8 × square root of (MHz / 30); these are not published HF specifications. M&P values use dB/100 m × 0.3048, with linear interpolation between listed frequencies. LMR-400 uses its published equation. Two decimals indicate calculated values, not measurement accuracy.
Flexibility and outdoor durability
| Property | ABR400 UF | UltraFlex 10 | ExtraFlex Bury 10 | LMR-400 |
|---|---|---|---|---|
| Flexibility | 19-strand copper center; flexible design. [1] | Stranded center; manufacturer supports tight bends and rotor use. [2] | Stranded center; designed for burial and flexible routing. [3] | Solid center conductor; best treated as a fixed run with broad bends. [6] |
| Bend guidance | Obtain current minimum bend radius for ordered assembly. | 80 mm radius up to 15 bends; 40 mm for a single bend. [2] | 80 mm radius up to 15 bends; 40 mm for a single bend. [3] | Installation bend radius 25.4 mm; repeated bend radius 101.6 mm. [5] |
| Sun exposure | Black PE jacket. Confirm UV rating for exact supplied part. [1] | UV-resistant black PVC. [2] | UV-shielded PE. [3] | UV-resistant black PE jacket. [6] |
| Water and soil | Supplier describes UV and burial jacket; confirm exact SKU suitability. [7] | Use above ground; manufacturer directs burial users to other models. [4] | Explicitly specified for outdoor use and direct burial. [3] | Standard LMR-400 is outdoor PE; use LMR-400-DB for direct burial. [8] |
A minimum bend radius is not a guarantee of continuous flex life. Provide a broad service loop at a rotator, secure the stationary cable, and keep twisting force away from connectors. Do not force any cable around a sharp corner or pull it by its connector. These are installation recommendations, not comparative fatigue-test results.
Sun and water exposure
UV resistance addresses jacket degradation, not a fixed service life in years. Sun also heats the cable; temperature can increase loss and reduce allowable power. Position cable away from hot roof surfaces where practical. Inspect exposed jackets and seals periodically for cracks, abrasion and movement.
Keep water out at connector interfaces, cut ends and jacket damage. Use a drip loop and a connector-compatible outdoor sealing system. Heat shrink at the cable termination alone does not necessarily seal the mated PL-259 to SO-239 interface. Do not assume a burial-rated jacket makes the complete assembly suitable for permanent submersion.
Ground burial
For direct soil contact, choose ExtraFlex Bury 10 or an ABR assembly explicitly confirmed for burial. Protective conduit can make replacement easier and reduce damage from stones or digging, but underground conduit can collect water. Keep joints accessible and above grade where practical; a buried splice needs its own suitable enclosure and sealing system. For the Times benchmark, use the dedicated LMR-400-DB variant when burial is required; standard LMR-400 data alone does not establish that rating. [8]
UHF connector performance
PL-259 plugs mate with SO-239 sockets and are a practical choice for HF amateur radio feed lines. Amphenol describes the family as having nonconstant impedance, but its nominal frequency range comfortably includes 3 to 30 MHz. Correct assembly and weather sealing matter more here than changing the connector family solely to improve HF loss. [9]
Use the connector specified for the exact cable dimensions and conductor construction. Similar outside diameter does not guarantee identical preparation dimensions, center-pin fit or crimp requirements. Avoid unnecessary adapters and provide strain relief.
The loss table excludes connectors, adapters, lightning protection and antenna mismatch. There is no defensible universal loss allowance for two unspecified PL-259 connectors. As an illustration only, adding 0.10 dB total accessory loss to a 0.61 dB cable produces 0.71 dB total loss and about 85 W output from 100 W. This is an assumed allowance, not a measured connector specification.
Purchase and installation decision
Choose ExtraFlex Bury 10 for a single cable covering exposure and burial. Choose UltraFlex 10 for flexible above-ground routing. Choose ABR400-UF when its assembly, local availability or termination service is preferable, after confirming UV and burial suitability for the ordered part. Choose standard LMR-400 as a fixed-run benchmark, allowing broad bends and a flexible jumper where repeated movement occurs.
Before ordering, specify the actual routed length including service loops, the highest operating frequency, both connector types, and whether any portion contacts soil. After installation, check continuity and shorts, then assess return loss or SWR across each operating band. A low shack-end SWR alone does not demonstrate low cable loss.
Sources and calculation notes
1 ABR400-UF manufacturer data sheet Open source
2 M&P UltraFlex 10 data sheet Open source
3 M&P ExtraFlex Bury 10 data sheet Open source
4 M&P UltraFlex 10 product and burial guidance Open source
5 Times Microwave LMR-400 attenuation data Open source
6 Times Microwave LMR-400 product specifications Open source
7 KF7P ABR assembly supplier description Open source
8 Times Microwave direct burial cable family Open source
9 Amphenol RF UHF connector specifications Open source
Sources accessed October 19, 2026. Power out = power in × 10^(−loss/10). LMR-400 loss = 0.122290 × √MHz + 0.000260 × MHz, in dB/100 ft.