Choose the Right Cable Jacket Material

July 17, 2013 at 10:00 AM


Plenum, LSZH and More

 

L-com's Plenum rated multiconductor cable

 

For buyers and technicians using signal-grade cabling, much attention is usually given to the connector type, termination process and bulk cable construction. Another aspect not to be forgotten that can be critical to many applications is the cable jacket material.

 

 

What does the jacket do?

 

More than just a color coding cable management technique, the jacket has several important functions. It allows the separate conductors to be organized into a single data line for ease of organizing, or it can even contain several conductors or wires to be broken out at a drop point.

 

The cable jacket also aids tremendously in the cable's flexibility and durability. In covering any shielding within the cable, it can prevent noise that collects on the shield from degrading the signals of other cables nearby, or from draining at inappropriate spots. Finally, the outer jacket is often the last line of defense between the data-carrying conductors and the environment in which the cable is used.

 

 

Fire Code Considerations

 

Comparison of cable jackets burning

Perhaps the most important aspect of a cable's jacket is how that jacket burns in a fire. PVC, the flexible plastic material that makes up most general purpose or residential grade cables is cheap and convenient, but it burns quickly and releases poisonous gas while burning.

 

If cables are run behind the walls of a building or in a vehicle and a fire breaks out, that fire can "leap" from room to room or floor to floor by burning along the cables behind the walls. And if the location where the cables are run is difficult to exit, as in a submarine, ship, airplane or even crowded warehouse, the poisonous smoke would compound the difficulty in dealing with the fire.

 

Because of this, many cables are given flammability compliance codes to help technicians from buying or using inappropriate cables. But, differences in measurement techniques and designations can make the process very confusing. In general, though, there are two "types" or classes of jacket materials other than PVC.

 

 

Plenum for Fire Retardation and Self-Extinguishing

 

In many large buildings, the duct work between rooms and floors is also the raceway for much of the building's data cabling. This space is often called the building's "plenum", and so the types of cables run in these environments are often called Plenum rated cables or just Plenum cables.

 

Plenum materials must be self-extinguishing, meaning that after they start burning and then the external fire or heat source is removed, the material must stop burning. This prevents the cables from "carrying" the fire to another location in the building and re-igniting unexpectedly. Sometimes Plenum cables are referred to as CL2P, OFNP, or CMP. Plenum cables are known to be more expensive than PVC, but in cases where a fire code requires plenum the cost must be factored into the overall installation job.

 

 

Low Smoke, Zero Halogen (LSZH) for Sealed or Mobile Locations

 

Jacket materials that have been designed to release very little smoke and no poisonous gas when burned are often called LSZH. These are typically reserved for special applications where the occupants near the cables may not be able to escape or ventilate the room in the instance of a fire. Again, this occurs frequently in military and aerospace applications.

 

 

Special Jacket Considerations

 

In addition to the above designations for particular fire codes, jackets may have other features useful in niche applications. UV resistance is important in applications where the cable may be exposed to strong sunlight for long periods. UV light can weaken and eventually destroy many PVC compounds over time. Or, oil resistance may be needed in many factory automation apllications as the petroleum-based compound could dissolve if immersed in oil. High-flex or hi-flex cables often use a special jacket that will not crack and split when the cables are flexed over and over again.

 

If you're looking for industry's largest selection of off-the-shelf Plenum, LSZH and other special-jacketed cable and cable assemblies, stop in at L-com's online configurator or contact customer service to get a quote started. We can custom manufacture cables with the jacket type you need.

 

How to Install Wireless Amplifiers

July 10, 2013 at 10:00 AM

 Setting up a WiFi Booster for an Indoor Wireless System

 

An Assortment of WiFi Amplifiers

If you do not work with wireless components every day, the prospect of adding a new component to boost the power of your signal may seem daunting. While we always recommend you have a professional install communications equipment to ensure it is done correctly, this brief tutorial will give you the basic steps to set up a simple WiFi booster. If it helps, you can also take a look at the video in this post or visit our complete tutorial here.

 

 

 

If you have a WLAN setup that requires a stronger signal, a simple WiFi booster may do the trick. Due to FCC regulations, if you are doing this installation in the United States, you need FCC approval to buy the amplifier. If you don't need an amplifier with power over 1 Watt, you can purchase an FCC certified amplifier kit which requires no special operator's license. Either way, most setups follow this simple procedure.

 

Diagram of an RF amplifier setup

On the amplifier, you will typically see two coaxial cable jacks, one labeled "Antenna" and the other labeled "Radio". There should also be a power jack (usually a DC jack requiring an external power adapter), which is where the amplifier gets the power to repeat the signal.

 

Using low-loss coaxial cable, simply connect the antenna to the antenna jack on the amplifier, and the radio (or access point or router, etc) to the radio jack. Then, after the two sides are hooked up, attach the power adapter and plug it in. Most amplifiers have LED lights to indicate activity, which helps you to see if it is working.

 

It's that easy!

 

Quick note: L-com has a huge selection of top-quality wireless RF amplifiers for the 2.4 GHz WiFi band and 5.8 GHz WiFi band, as well as 900 MHz, 3.5 GHz, and 4.9 GHz frequencies. These ampifiers feature HyperLink's® Active Power Control (APC), which automatically maintains a constant output power regardless of the length of the attached cables. Aside from the indoor wireless amplifiers, L-com also carries HyperLink® brand outdoor wireless amplifiers for all-weather operation.
 

Tutorial on Coaxial Cabling

July 3, 2013 at 10:00 AM

 

 

 

Coax is one of the most venerable cabling standards having been developed for the US military over 50 years ago. Unlike some standards that were popular for a while and eventually became legacy, coaxial cabling is still very relevant and used in a lot of common applications. It is a robust and reliable cable type with no sign of going away any time soon.

 

 

 Types of Coax Cabling

 

As you can imagine, over the years that coax has been around, many variations have been designed for specific applications. We will talk about the Radio Guide (RG) styles and the low-loss styles that were made popular by Times Microwave's LMR® standard. Though there are many other coax options like mini coax, twinaxial and tri-axial, the applications for those have dwindled in recent years.

 

 

RG-style Coaxial Cable

 

The original Radio Guide standard called for a number followed by codes to determine specific aspects of the cable (such as jacket type, center conductor material, etc.). However, today many of the standards have become "soft" meaning that RG58B/U, for instance, may have very different characteristics from manufacturer to manufacturer.

 

Exposed view of a coaxial cable

Most RG numbers refer to cables made with specific diameters (as thicker diameters typically have lower attenuation over long lengths), shielding, jacket type, and dielectric type. The dielectric is important as it can control the "characteristic impedance" of the cable. In general, cables with a characteristic impedance of 50 Ohms are used in data and wireless network applications, and cables with a characteristic impedance of 75 Ohms are used in higher bandwidth audio/video applications.

 

The bottom line about RG-style coax cable: if you need to get a specific type for your application, you should include the characteristics of the cable with your request. The actual standard may have some variations that would make the off-the-shelf product unsuitable for some circumstances.

 

 

Low-loss Coaxial Cable

 

Low-loss cable is almost exclusively used in wireless applications. It is ideal for any antenna-to-radio setup, and is often used extensively in wireless system installations. Low loss cable is often referred to by its series number, such as 200-Series cable, which is usually a rough approximation of the diameter of the cable. The higher the number (ie, 400, 800, etc), the thicker and heavier the cable, and the less attenuation over the length. Because of this, higher series numbers are typically used in cases where the antenna is permanently installed at some distance from the radio. Lower series numbers are used in cases where the antenna is closer, especially in portable setups where the weight of the cable is important.

 

 

Connectors

 

There are a large variety of coaxial connectors, usually designated by a letter or combination of letters. Most coaxial connectors are round or hex shaped, and can come in screw-on, push-on, or twist-lock designs. Be extra careful if you need a connector that is called "reverse polarized" or preceded with the letters "RP". These connectors are similar to the regular polarity versions except that the gender of the connector is reversed, making it unable to mate unless it is with another RP style connector. For a complete list of coaxial connectors with large images, try this coaxial connector chart.

 
If you are in need of coax: L-com has carried RG style coax cable and assemblies for decades, and together with our vast collection of low-loss coax cables it is one of the most comprehensive in the industry.
 

Low Loss Coaxial Cable for Wireless Applications

June 26, 2013 at 10:00 AM

 

Closeup of Low Loss Coaxial Cable Stripped to Show Components

Even in a wireless network, cables and wires are still used to connect components together (access points to amplifiers, amplifiers to antennas, etc). Each component needs cabling to interact.

 

If you are a wireless engineer and need to interconnect components, chances are you are using low loss coaxial cabling. While 50 Ohm RG-style coax is sometimes used, the attenuation is usually too much for any length over just a few feet. This is where low loss coaxial cable comes in.

 

 

Coaxial Cable and RG-Style Coax

 

All coaxial cable works the same way: the signal is run over two "axes" (thus the name). Coaxial technology is one of the oldest signal cabling types, and is still used today for a specific reason: it is robust and can carry a signal very well over a long distance. In general, the thicker the cable, the less "loss" or attenuation of signal there is over the length of the cable.

 

The original standards for coaxial cable were set forth by the US military. These cables used the term "RG" (for "Radio Guide" or "Radio Government") followed by a number to designate the standard. This worked well at the time, but as technology became more and more utilized in commercial and non-military applications, the restrictions of the standard became less rigid (to the point where RG316, for instance, may have very different properties today depending on who manufactures it).

 

 

Times Microwave LMR® Cables

 

No matter who makes the RG-style cables, they have one fundamental problem: the signal degrades over the length of the cable until it is no longer useable. For shorter use in labs or machine-to-machine applications, this is not a problem. But in wireless applications, the signal integrity up until it is broadcast through the antenna is critical.

 

For that reason, Times Microwave Systems developed a low loss version of coax that it branded as its LMR® series coax. The newly-engineered solution offered far lower loss and better RF shielding, making them a much better choice for wireless systems than the RG styles.

 

Outside of Times Microwave Systems' product (the term LMR® refers specifically to Times Microwave Systems product and is trademarked for their use), several other companies now offer low-loss coaxial cables. These generally follow a similar naming convention as what Times Microwave Systems uses: a three-digit "series" number that refers to both the thickness of the cable and the low loss properties.

 

For instance, 100-series low loss coax is thinner and has greater loss than 200-series, which is thinner and has greater loss than 400-series, etc.

Diagram of most common low-loss coaxial cables

Note that with thicker cable factors such as cable weight and flexibility must be considered. However, there are now ultra-flex versions of thicker series like the 400-series that offer similar loss characteristics but are far more flexible.

 

Quick note: L-com has been manufacturing high-quality coaxial cables and components for over thirty years.
 

DB9 D-Subminiature Connectors : Advantages and Disadvantages

June 19, 2013 at 10:00 AM

9-pin D-Sub connectors (DB9 or DE-9)

 

DB9 Connector on Cable

For many years, serial communication was one of the chief methods of connecting peripherals (such as joysticks, printers, and scanners) to PCs. The most common connector type for serial communication was the 9-pin D-Subminiature connector, or sometimes called a DB9 or a DE-9.

 

Nine pins were plenty to carry the data in series, and though there were many drawbacks to DB9 connectors which eventually lead to them becoming legacy in favor of standards like USB, there are still many devices with DB9 ports or cables on them today.

 

 

What are the disadvantages?

 

The connectors themselves are large, making them difficult to connect and disconnect in tight spaces. Also, the pins are exposed in the shell, so they can be easily bent or broken off. Though the connector can be mated without using the thumbscrew hardware, it does not tend to hold as well using just friction-fitting. If you do use the thumbscrews, the connector takes much longer to plug in and unplug.

 

Finally, serial communication tends to be slow, especially over longer lengths, and unexpected breaks in communication could cause software on the PC to freeze. All of these problems led to other standards becoming more popular for the same applications.

 

However, this does not mean that the DB9 connector is a lost cause. There are actually solutions available for many of the problems mentioned above. For instance, right angle adapters solve the tight-space problem by allowing a tight angle without damaging the connector. Widely available D-Subminiature plug and jack covers can protect pins from damage when not mated, and adapters like gender changers and socket savers can reduce the stress caused by repeated mating cycles.

 

 

On the other hand...

 

ES4-232 4-Port Ethernet to DB9 Adapter and Device Server

DB9 connectors have advantages too. In general they are far easier to customize, with at least 9 individual pins to carry serial data. Though the speed is slower than other standards, the length of the cable can be much longer. USB, for instance, has a five-meter length limit, but RS-232 (the most common standard for serial data) has no defined length limit, and RS-422 has been used at lengths hundreds of meters long with special equipment.

 

Also- Don't worry if you have an old device that only has DB9 connectors on it. Even with D-Subminiature being mostly legacy, there are plenty of options for conversion. Converters to and from USB, Ethernet, and other standards are common and can allow you to use your device on any computer today.

 

Examples of Applications for Serial Converters

If you're looking to find DB9 Connectors: L-com carries products ranging from economical serial cables with many off-the-shelf lengths to high-quality premium cables for demanding applications. Also check out L-com's D-Subminiature adapters for innovative solutions to common problems, and L-com's bulk cable, connectors, adapter kits and tools for do-it-yourself components.
 
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