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Charles Industries, LLC
An Amphenol Company

1450 American Lane
20th Floor
Schaumburg, IL
60173-5492 USA



Superior Load Coils from the Industry Originator

For more than 40 years, Charles Industries (formerly Coil Sales) has pioneered load coil technology to develop the highest performing, most reliable coils available anywhere. Our very first product manufactured was the revolutionary single-entry load coil. Today, our coils serve in the vast majority of RBOC, CLEC and IOC networks, helping bring phone service to every corner of the globe.

Charles Load Coils are furnished with a high permeability, nickel core made to our precise specifications to guarantee lower DC resistance. Matched bifilar quadruple-insulated windings ensure nearly perfect DC and inductive balance. Mechanical connectors have replaced solder connections, acting as a heat sink and eliminating intermittency in transmission due to cold solder joints. Charles Load Coils provide a non-expanding encapsulant with the lowest viscosity available. This encapsulant ensures total penetration, provides a superior pressure dam, and absorbs thermal shock.

Charles Load Coils

View Load Coil Datasheet (.pdf)

How Load Coils Work

All subscribers and trunk cable facilities consist of resistance and capacitance. The resistance is determined by the length and gauge of the cable conductors. The capacity is determined by the length of the cable conductors and the spacing between the conductors

The capacitive effect of the cable conductors has a direct relation on the voice band (300 Hz to 3000 Hz) from any given point. The higher the frequency, the greater the loss or attenuation (3000 Hz would be attenuated more than 300 Hz). By adding inductance (load coils) periodically into the cable facility, the capacitive effect can be cancelled, thus causing the attenuation across the voice band to be equal. Non-loaded subscriber loops should not exceed 18,000 ft. of cable. It is recommended that loops longer than 18,000 ft. be conditioned with load coils.

Optimum loading can be achieved by selecting the desired loading coil, measured in millihenries (mh), and placing them in the cable plant at prescribed intervals. For example, an 88mh coil will cancel 6000 ft. of capacity. Therefore, the recommended spacing would be at intervals of 6000 ft., with the first coil place 3,000 ft. from the start of the cable run.

The standardized Charles Load Coil is the mini H88 (88mh inductance, 1.3 diameter, 6,000 ft. spacing). Custom coils can be special ordered from Charles for inductances not shown (i.e. 66mh, 44mh, 22mh, etc.) by contacting your Charles Sales Representative. Physically, Charles Load Coils are available in two sizes, standard (1.72 inch diameter) and mini (1.3 diameter).

Kwik Kase™ Load Coil Cases
Every modular component, load coil, build-out capacitor, saturable inductor, etc., is exactly the same diameter: 1.3 inches. They are standardized so that you can snap them into our midget B-152 Kwik Kase according to your needs rather than having to order specially built combinations. Kwik Kases encapsulate load coils within a tough ABS plastic shell, providing perfectly sealed protection.  They are then easily mountable to pedestal brackets and backboards for convenient splicing access and quick installation.

With Kwik Kase Load Coil Cases, you'll save not only time on deliveries and installations, but also on overall costs too, because the modules can be returned to stock for future use. With all these cost advantages, it's gratifying to know that the module also improves electrical and physical properties. Kwik Kases can be special ordered for non-standard sized load coils in addition to the standard mini H88 coil.

Charles Kwik Kase Load Coils

Load Coils and DSL Deployment

Because load coils limit the high-frequency spectrum that is used for high-speed data transmission, ADSL and other broadband connections cannot be effectively deployed on circuits loaded with standard coils. Charles’ solution is the Smart Coil™ DSL Line Conditioner. With Smart Coils, customers can receive ADSL services over the same copper pair that currently transports their POTS service, even beyond 18Kft. Smart Coils provide all the voice quality enhancement of a common load coil, yet are transparent to ADSL. They allow for easy turn-up or turn-down of broadband services. By using Smart Coils in place of common load coils, service providers can immediately and cost-effectively deliver broadband services over a wider coverage area.


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