What is unique about opal?

Cable ends different - Is there a "good" and "bad" side?

The aim is to bring the cable with its properties as close as possible to the contacts of the plug to provide an optimal data transmission. The distinctive physical properties of a data network cable are firstly, that each pair is twisted and secondly, that the pairs are in a defined position to each other. The structure and symmetry properties characterize the impedance, ideally 100 ohm.

The cable design (whether shielded or unshielded) is illustrated by the following picture. What you see at each cable end is a pair at the top, at the bottom, on the left and on the right, like crosshairs. If you rotate both ends of the cable so that both sides of the same colour pair are located at the bottom (e. g. in the picture: blue and white) you will see that generally one pair is on the left hand side and one on the right hand side, thus mirror-inverted, on both cable ends (here: brown-white and orange-white).

The RJ45-connector with two different cable managers

This connector removes the above-mentioned problems. Each side has its own cable manager. It is structured like a cross with 4 channels: smoothly the pairs are led to the contacts according to their location in the cord. The symmetry of the cord is maintained!

In a refined way, the pairs of pins 4 + 5 and 3 + 6 are led directly to the contacts without intersection. If pairs come too close to each other, the unwanted crosstalk impends. An important evaluation criterion therefore is the parameter Near End Crosstalk (NEXT).

Which pair is led to which pin is determined by the standards EIA / TIA 568A or B.

Sharp bend protection

An efficient sharp bend protection prevent a too small bending radius of the cable. The locking extension prevents the breaking off of the tab. At the same time it facilitates the unlocking of the connector. The small width of the design allows an outstanding handling of active components with a high number of ports.

The Patchcord

For the MeiCord opal cable we use a wire with the diameter AWG 24/7 for the conductors AWG 24 represents a cross section of 0.22 mm², the 7 stands for seven fine wires. Often patch cables are tailored with AWG 26/7 (0.14 mm²) of AWG 27/7 (0.11 mm²). Due to the smaller cross-section these show a worse performance in the attenuation.

The combination of plug and patch cable

The selection of a suitable cable with very good measurements and also an excellent plug are no guarantee for a good mix of both. It takes a lot of effort to harmonize the components, taking into account the different parameters. But precisely here lies the problem! A Cat6-plug and Cat7-cable do not automatically result in Cat6!

Our many samples prove the assertion. Sometimes not even Cat5 is obtained. There just a few manufacturers who have the know-how. A quality-assessment certainly is the measurement protocol, but again you have to make sure according to which norm the measurement was performed. The following parameters are always discounted: cycles of operation, contact height, strain relief, bend protection, temperature behavior etc.

Measurement Protocol: What is measured?

(Please click on the image to enlarge)

There are very few vendors in the market who sell their patch cords including measurement protocol. You should always make sure that the patch cord is measured according to the standard Category 6. Why? Because the requirements (limits) for the measurement of individual components are much stricter than in other measurement models. An example: There is the measurement model Channel Link. Here, an entire system is measured, which consists of a fixed line installation and at least two patch cables. The largest port of the setup here is made up by the installation route and not the patch cable. Moreover, the limits of the channel are well below those of the measurement components. Even measurements up to 500 MHz in the channel do not definitely prove Cat.6 according to the component standard. As an aside should be mentioned here that the Cat6A that forms the basis for the 10 Gbit/s has not been completely adopted in defining the test socket.

We have the MeiCord patch cords measured to the American TIA component standard with a minimum of 1dB reserve (selection). Compared to the ISO or EN Cat6 standard, TIA is 0,1 to 0,4 dB sharper at NEXT, depending on the frequency range up to 250 MHz. A cable-related and individual print-out of the measurement protocol with the most important parameters NEXT and Returnloss, based on the worst pair with graphical representation is provided with each MeiCord opal. The 1 dB-selection prevents disagreements with other instruments and in the measurement tolerances.

Outlook

We will increasingly deal with the still new measuring methods according to the new Cat6A component standard for patch cords. What does the practice in that regard look like? Shielded or unshieldes at Hifi? High NEXT-reserve = great sound? Questions that need to be resolved. Assume that we will get to the bottom of these things.