The following information was provided by one of my readers. “Switchman” as you will see, has extensive experience in telephony. Read and heed and add another arrow in your quiver.
I’m going to apologize up front if any of this info is too elementary. I don’t know how much experience you have around telephony, so I am just going to assume an average layman’s base of knowledge. Tracers (also called toners or tone generators) are most often used to locate specific pairs of wire over long distances. Most also have the ability to provide enough battery to allow voice comms with buttsets across a dead or “dry” pair. Here’s a link to an example tone generator made by JDSU that has the talk battery feature. http://www.electriduct.com/JDSU-TG101-Tone-Generator.html
In the phone business we deal with massive bundles of wire that are often times snarled and resemble a rat’s nest. Even in the best conditions, just trying to find one individual pair of wires out of an 1800 pair cable can be virtually impossible if the color-coded binders have aged and changed colors. There are also relatively ancient cables where the individual pairs are all white. We refer to those as “tone cables” because the only way to find your pair is to put test tone on it at one end and then find that tone on the other end with an inductive probe.
When performing maintenance you often have techs on either end of a cable. One way they can talk to each other is to find a dead pair (no battery on it), then put test tone on it at one end with the toner. The tech at the other end finds the pair with an inductive probe or sometimes even with just a buttset. Once the two techs know they are on the same pair, the toner can be placed in series with a buttset and switched to “talk battery” mode to provide the voltage needed to carry voice over the dead pair. The other end just uses a buttset, you only need one toner to provide battery.
I can’t find specs for the range of voice comms using this method, but these little toners can send test tone over 10 miles. To put a toner in series with a buttset simply connect one lead from the buttset to one lead on the toner, the two remaining leads are used to connect to the pair being used for comms. When being used in this configuration, the end with the toner can “ring” the other end by simply switching to test tone and then back to talk battery. It won’t actually ring the other buttset, but it will generate that same warbling 2 freq test tone on the other end used to locate the pair in the first place.
I hope I haven’t lost you at this point. If there is anything I can clarify about this setup or any other telephony info please let me know. I’ve been working for a “Baby Bell” for 15 years and grew up around it as well.
Thanks for the info. Switchman, feel free to contribute at any time. That goes for the rest of you folks out there in the blogosphere that have communications technical experience that is pertinent to our mission (METT-TC). This is not a one man show.