This calculator calculates percentage braid cover using the method specified in ANSI/SCTE 51 2007.
Use consistent length units for all input data, you may for example use cm, m, inches, but be consistent.
The calculator does not do a lot of error checking, if you enter nonsense, it will produce nonsense.
Fig 2 shows two example RG58C/U style cables, dimensional units are based on metres. They are:
Example 1 clearly has a poorer braid, but for all the bad appearance, it is 78% coverage... you have to 'run the numbers' to find the actual coverage, especially when the cover becomes uneven. Once coverage drops below 90%, there is insufficient braid to ensure that it is evenly distributed over the dielectric. This cable is probably representative of better budget cables, and it can be seen that the Belden 8262 is a better product (more wire, tighter helix, gives better coverage) it is nearly ten times the price in Australia.
To use the calculator effectively, you must have quite accurate measurements of the braid strands, and that is probably beyond a digital caliper, I use a micrometer.
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