OSP Expert: Don McCarty

Series Resistance


Its Effect on Bandwidth Circuits on the Copper Infrastructure In my July 2016 column, “What Is a Good DSL Circuit?”, Vernon May mentioned 66 blocks and DSL.* Later, in a McCarty newsletter, Vernon responded to a reader question concerning 66 blocks in outside plant. In this month’s column, we will again look at the issue of 66 blocks, and the effect of series resistance on copper circuits in general. When we look at any connection of copper conductors, that connection must be 0 ohms at any frequency. Any series resistance, even as low as 5 ohms in series on paired…

5 Questions About Fiber Optic Bonding, Grounding, and Locating


One of our readers asked us this question. “What needs to be grounded in a fiber optic network?” The standard answer of “everything” seemed illogical and was unsatisfactory to him. Our research so far has yielded many more questions than answers. We want to share these questions and our impressions with our readership. Legacy Good bonding and grounding has long been an indication of quality craftsmanship in the outside plant (OSP) network. In copper cables, bad things happen if we don’t do it. •  There are safety hazards. •  The cables become susceptible to power influence and other external noise…



Vernon May and I wrote this column, and we want to let you know the topic will be discussed further by us at ISE EXPO 2016 in our seminar. So please join us in San Antonio, September 20-22. When you ASSUME…. We all know the rest of that saying. However, assumptions are a necessary part of troubleshooting and of life in general. When we leave for an appointment, we generally time it based on the assumption that our car will start and the freeway is not locked up again. Assumptions have a vital role in communications circuit trouble shooting. They…

What Is a Good DSL Circuit?


This month’s OSP Expert is written by guest author and DSL expert Vernon May. I work with Vernon, of Vernon May Solutions, providing training and consulting services. A while ago, we began discussing the parameters for defining a good DSL circuit. We hope you find this month’s column helpful — and please, please, please, send us any follow-up questions or comments. —Don Don and I get a skewed view of the DSL troubles encountered in the field. Often, we are called in as the last resort. Therefore, we work with the most difficult troubles (and the smartest technicians). Granted, these…

Transporting 3 Totally Different Circuits on the Same Copper Cable Pair


DSL and IPTV were introduced by handing the technicians a test set and watching for pass/fail like we did in the POTS environment. Sixteen years after the advent of DSL, problems in provisioning and maintaining these circuits still persist that were caused by this practice. The biggest myth is: if the circuit is properly designed and is free of DC type faults with good bonding and grounding and is within the reach for that particular POTS, DSL, or IPTV service, then that individual service should function properly. There is a bit more to it. I have preached this constantly: Many…

The Value of Longitudinal Balance in DSL Circuit Evaluation


As we are writing this column, both Vernon May (a bandwidth expert) and I are training together on a combination DSL – cable fault locating course in Tennessee. We are teaming up on this month’s column to discuss the longitudinal balance test. It is one of many discussions that we get into on providing quality bandwidth. I have been preaching for years that if you are going to provide bandwidth over the copper infrastructure then the copper infrastructure must be stellar, and the longitudinal balance test properly applied and interpreted — and this will indicate the health of any copper…

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