LMR-400 Coaxial Cable Info
Cable for most all CB, Ham and WiFi installs needs to be 50 ohms; cheaper cable not meeting this standard or cheap mismatched connectors significantly increases signal loss. It is more expensive to manufacture 50 ohm cable than 75 ohm, so many cheaper producers tend to substitute without telling or use cable with variable dielectric thickness and copper alloys less than 95% pure for poor conductivity. Certain Chinese plants make cable for a large number of resellers and as copper prices go up, the quality of the alloy used tends to go down to maintain a price point.
U.S. Made LMR-400 Coaxial cable should not be confused with the imitations sold calling themselves LMR400 in most eBay listings. There ARE other quality coax producers out there other than Times Microwave. We sell a couple ourselves, but please - if you don't buy here do your homework.
Coaxial cable design choices affect physical size, frequency performance, attenuation, power handling capabilities, flexibility, strength and cost. Skinny cable has less metal to conduct your signal and causes more loss.
Cable MUST be precision manufactured with precise standard spacing between conductors to avoid significant signal loss. Quality control is Key!
Signal losses are frequency dependent, the losses becoming higher as the frequency increases. It is not unusual to experience 5 times as much signal loss at 6 GHz than at WiFi's 2.4 GHz. Installing a 15Db gain antenna and running cheap antenna cable can result in cable loss of twice your antenna gain. Don't bother buying a good antenna if you are running cheap cable. Losses can be reduced by increasing the diameter of the cable. A cable with twice the diameter will have half the signal effect resistance loss. Assuming cable quality is equal, the larger cable would halve the dB/meter loss. In designing a system, consider not only the loss in the cable, but also the loss in the connectors. Cheap connectors give you as much loss as cheap cable. On a final note, poorly made LMR600 "type" cable can have a greater signal loss than good LMR400.
This is Top Quality LMR400 50 Ohm Cable. All common Radio Frequency (RF) devices CB, Ham, WiFi, Packet Radio, etc. are to be used with 50 Ohm cables and connectors. 75 Ohm cables and connectors are designed for low frequency signals like Video or Cable TV and are unsuitable for most all RF installations. Each type of coaxial cable has a characteristic impedance (resistance) depending on its dimensions and construction, which is the ratio of the voltage to the current in the cable. In order to prevent reflections at the destination end of the cable from causing standing waves. The equipment "appears" electrically similar to a continuation of the cable, preventing reflections that cause signal degradation.
In high quality cable the dimensions and spacing of the conductors are uniform. Any abrupt change in the spacing of the two conductors along the cable tends to reflect radio frequency power back toward the source, causing a condition called standing waves. This acts as a bottleneck, reducing the amount and quality of the transmitted power. To hold the shield at a uniform distance from the central conductor, the space between the two is filled with a plastic dielectric designed to maintain the proper spacing between conductor and shielding to assure maximum signal transmission and lowest loss. Manufacturers specify a minimum bend radius, to prevent kinks that would cause reflections. You should allow three inches of cable to make a 90 degree turn in your runs without causing signal loss. The connectors used with the coax must also hold the correct spacing through the body of the connector to avoid signal loss. The transmission of energy in the line occurs totally through the dielectric inside the cable between the conductors. This cable can be bent and moderately twisted without negative effects, and can be strapped to conductive supports without inducing signal interference.
LMR-400 cable is designed for outdoor applications, can be direct buried, and the outer jacket resists ultraviolet light and oxidation. There is no environmental restriction on use for indoor installations.
Our LMR400 cable is the FR version for indoor/outdoor installs certified as fire resistant as required by the Pennsylvania Bureau of Mines. It has all the UV protection of standard LMR with a higher flash point and non-halon certification. Times Micro developed the variant for industrial applications wanting to run continuous cable runs indoors, underground and between structures while meeting all OSHA and PBM standards.