LMR-400 vs LMR-240: Choosing the Right Low-Loss Feedline
LMR-400 and LMR-240 are both Times Microwave low-loss cables with similar construction. The main differences are diameter, flexibility, and loss. LMR-240 at 0.240" is significantly more flexible and easier to route through walls and conduit. LMR-400 at 0.405" is stiffer but delivers meaningfully lower signal loss, especially at higher frequencies.
The Short Answer
For runs under 50 feet or installations requiring tight bends and conduit routing, LMR-240 is the practical choice. For runs over 50 feet, cellular boosters, or any 2.4+ GHz application, LMR-400's lower loss justifies the extra bulk.
Key Differences at a Glance
- At 2.4 GHz, LMR-400 loses 6.8 dB/100ft vs LMR-240's 10.8 dB — significant on longer runs
- LMR-240 has a 1.5" minimum bend radius vs LMR-400's 2.0" — easier to route
- LMR-400 weighs about twice as much as LMR-240 per foot
- Both use the same foamed PE dielectric and bonded foil + braid shield construction
- LMR-240 costs less per foot and is available in UltraFlex version for tighter routing
Side-by-Side Specifications
| Specification | LMR400 Times | LMR240 Times |
|---|---|---|
| Impedance | 50 Ohm | 50 Ohm |
| Frequency Range | DC – 6 GHz | DC – 6 GHz |
| Velocity Factor | 0.85 | 0.84 |
| Dielectric | Foamed PE | Foamed PE |
| Shield | Aluminum foil + tinned copper braid | Aluminum foil + tinned copper braid |
| Jacket | PE | PE |
| Center Conductor | Bare copper clad aluminum, 2.74mm | Bare copper clad aluminum, 1.42mm |
| Min. Bend Radius | 2.0 in (50mm) | 1.2 in (30mm) |
| Max Voltage | 600 VRMS | 600 VRMS |
| Temperature Range | -40°C to +85°C | -40°C to +85°C |
| Weight | 5.0 lb/100ft | 2.5 lb/100ft |
Attenuation Comparison (dB per 100 ft)
| Frequency | LMR400 Times | LMR240 Times | Difference |
|---|---|---|---|
| 100 MHz | 1.5 dB | 2.4 dB | +0.9 dB (LMR240 Times worse) |
| 450 MHz | 3.3 dB | 5.3 dB | +2 dB (LMR240 Times worse) |
| 900 MHz | 4.7 dB | 7.5 dB | +2.8 dB (LMR240 Times worse) |
| 1.8 GHz | 6.8 dB | 10.8 dB | +4 dB (LMR240 Times worse) |
| 2.4 GHz | 7.9 dB | 12.6 dB | +4.7 dB (LMR240 Times worse) |
| 5.8 GHz | 13 dB | 20.6 dB | +7.6 dB (LMR240 Times worse) |
When to Choose Each Cable
Choose LMR400 Times when:
- Antenna runs over 50 ft
- Cellular booster installations
- 2.4 GHz and 5 GHz applications
- Tower feedlines and base stations
Choose LMR240 Times when:
- Runs under 50 ft
- Routing through conduit or walls
- Mobile vehicle installations
- Applications requiring frequent bending
Frequently Asked Questions
Is LMR-240 good enough for a cellular booster?
Yes for short runs under 30 feet. For runs over 30-40 feet at cellular frequencies (700-2100 MHz), LMR-400 is recommended to minimize signal loss between the outdoor antenna and the booster.
Can LMR-240 and LMR-400 use the same connectors?
No — connectors are sized for specific cable diameters. LMR-240 uses connectors for 0.240" cable and LMR-400 uses connectors for 0.400" cable. They are not interchangeable.
What is the practical difference in signal loss?
On a 75-foot run at 900 MHz, LMR-240 loses about 6.0 dB versus LMR-400's 3.5 dB. The 2.5 dB difference is significant — it represents roughly half the output power from your transmitter reaching the antenna.
Build Your LMR400 Times or LMR240 Times Cable
Pick your connectors, choose your length — hand-assembled and shipped free in the USA.