Tone generators and probes— simple yet essential tools in your kit

Today's tone generators and probes make it even easier to locate your circuits.

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Okay, so maybe tone generators and probes aren't the most exciting tools on the market. Nevertheless, installers and maintenance crews alike agree that tone generators and probes are still the most useful testing equipment in their tool kits. They may be simple, but today's tone generators and probes offer new features that make them even easier to use.

So, what's driving the market for these essential locators of both voice and data circuits that have been around for decades? Most industry professionals agree that it comes down to price, personal preference, and sometimes application—but most of all because it's something every installer and technician needs. (See table: download "Tone Generators and Probes" pdf)

"It's like a hammer to a carpenter. You can't go out on a job to install or troubleshoot cabling without a tone generator and probe," says John Perala, senior business development manager for Harris Corporation ( "There is a huge demand. And just like with carpenters and hammers, every installer has a personal preference for a certain tone and probe."

Satisfying the demand

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Triplett's Fox and Hound 2 kit features three distinct tones, polarity, talk battery supply, continuity, and both audio and visual signals.
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Ohio-based Triplett Corporation ( is best known for the Fox and Hound, a tone generator and probe with a unique name and recognizable packaging. The Fox produces a square-wave signal and features three tones—low, warble, and high. The Hound 2 operates by induction, and uses both audio and visual signals to alert the operator to the presence of tone or circuit location.

"Having three separate tones is effective in a large facility where more than one person may be doing the same work," says Mike Hahn, senior designer at Triplett. "Each user can set the Fox at a different tone to reduce confusion when locating circuits." According to Hahn, having two indicators on the Hound—an audio signal that gets louder and an LED that gets brighter—is exceptionally helpful in any environment where noise is present.

The Fox and Hound offer two different techniques for tracing wire—one that traces within a few feet and another within inches. "If the signal is applied between earth-ground and one of the wires in the pair, the probe picks up the signal a few feet away," explains Hahn. "This is useful if you're tracing the wire through walls. If the signal is applied between the two wires on the pair, the probe only picks up the signal within one or two inches. This technique helps locate a pair within a bundle of several pairs."

In addition to tone, the Fox includes two other positions. Off/line polarity tests for correct polarity on voice circuits. The talk/continuity position provides power and indicates continuity, such as in tracing point-to-point signals within a junction box. "During installation, when a building may not yet have power, the talk feature on the Fox provides enough power for using a buttset," explains Hahn. The Fox also includes alligator clips and an RJ-11 connector. For $92, Triplett's Fox and Hound 2 Kit (model 3245-K) comes with its own carrying case and a one-year warranty. Purchased separately, the Fox is $31 (model 3380), and the Hound 2 is $55 (model 3236).

MetroTel Corporation (, now a subsidiary of Independent Technologies, offers the MT139 tone generator, MT8629 inductive probe, and their latest AP2000 inductive probe. The MT139 tone generator produces a sine wave, offers two separate tones (warble and solid), and includes both alligator clips and an RJ-11 connector. It also features a short lanyard on which to hang the tone generator, preventing its weight from pulling off the clips during operation.

Filtering out noise

The MT8629 and AP2000 include both audio and visual indicators. The speaker is located on the end of the probes, which prevents muffling during grasping. A sensitivity control on the AP2000 lets you filter out noise and focus on a particular frequency, and it includes a jack for attaching an earpiece.

"When you attach an earpiece to the AP2000, the speaker turns off, and you hear the tone only through the earpiece," explains Larry Suder, MetroTel's vice president of business development. "This feature can be highly useful in a manufacturing environment, or other loud location, where noise from equipment and machinery can mask the tone." The $108 MT139 tone generator and MT8629 probe kit includes a leather holster-type carrying case. The AP2000 probe is sold separately for $49.

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Tempo's AT8L LAN Toner tests continuity and polarity, sends tone, and supplies talk battery to any pair, in any configuration. It also includes special features for identifying/flashing a hub or PC.
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Tempo Research Corporation, a Textron Company (, offers several tone generators and probes that range from inexpensive and simple to premium and intricate. Tempo's 711K Classic tone and probe kit (formerly Progressive) is widely used by technicians. The durable, weather-resistant tone generator offers three distinct tones, continuity and polarity testing, and talk battery supply. It includes both alligator clips and an RJ-11 jack.

The 711K's inductive probe includes audio and visual indicators, as well as recessed tabs for connecting a buttset. Its volume/sensitivity control offers precise identification when tone signal bleed is present. "We conducted several focus groups, and found out that users wanted to be able to step up the power of the tone and change the cadence without taking off the back of the probe," says Tempo's product manager Jim Carefoot. "Now, all the user functions are located right on the tone generator." The $99 711K comes with a woven dual carrying case, and all components are available separately.

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Tempo's 711K Classic tone and probe kit (formerly Progressive) offers three tones, continuity and polarity testing, talk battery supply, audio/visual indicators, buttset connectors, and volume/sensitivity control.
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Tempo's AT8 Series AdapToner is a combination of a tone generator and modular breakout adapter, which lets technicians test continuity and polarity, send selectable tone, and supply talk battery to any pair, in any configuration. "Category 5e and 6 wiring is a much higher quality cable with low loss, and usually, you're counting on that loss to generate tone and locate your circuit," explains Carefoot. "Tracing the signal is easier when connecting an AT8 series tone generator to one wire of two different pairs in eight-position modular jacks—an excellent tool for today's premise cabling systems." The AT8L LAN Toner includes special features for identifying/flashing a hub or PC. The $63 AT8 and $69 AT8L can be used with any Tempo probe, and include modular 8-position plugs and jacks for easy in-line testing.

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Harris Corp.'s Pro 2000 tone and probe kit comes with an earpiece, sturdy black pouch, and offers two separate tones, an audio indicator, and sensitivity control.
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Harris Corporation packages the $85 Pro 2000 tone and probe kit with an earpiece and sturdy black pouch. The sine-wave tone generator offers two separate tones, and the inductive probe has an audio indicator and sensitivity control. According to Harris' Perala, the probe's sensitivity control helps to identify a pair. "If you lower the volume, the sensitivity increases for higher accuracy on a pair," says Perala. "This means you have to get closer to the pair to identify it, which can be helpful in a messy bundle of cable."

In November, Harris started packaging the TS100 cable faultfinder with the Pro 2000 probe. "We want to emphasize that the TS100 also works well as a tone generator," explains Perala. "In addition to valuable faultfinding features, it offers a patented tone generation that even works in proximity to current-bearing cable." As a tone generator, the TS100 faultfinder changes tone when the cable condition changes to normal-open from any other condition. After attaching the TS100 faultfinder to one end of a pair, users can short the other end, and then identify the exact pair using the Pro 2000 probe.

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Harris Corp.'s TS100 cable faultfinder works well as a tone generator, changing tone when the cable condition changes to normal-open from any other condition.
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The moisture-proof TS100 faultfinder detects voltage on a line, and it displays the distance to an open or short on the pair. "The TS100 is also a great tool for managing inventory," says Perala. "You can connect it to one end of a spool of wire, and it will tell you the distance to the other end, or how much wire you have left on the spool." The $295 TS100, value packaged with the $55 Pro 2000 probe, is available for $324.

Spanning the industries

Tone generators and probes are practical installation and troubleshooting tools that can help accurately identify a pair or conductor within a bundle, at a crossconnect point, or at a remote end. Used on any twisted pair wiring, single conductors, coax cable, or de-energized AC wiring, there is a big demand for tone generators and probes in the cabling industry, as well as in many other industries.

"Although they originated in the telephone industry, where hundreds of wires in a bundle make it easy to lose track of a pair, tones and probes have been adapted for use in almost every industry, from marine and military to alarm and automotive," says Triplett's Hahn. "Some are designed to be weather-tight for outside use, and others offer sensitivity, filters, or earpieces for noisy environments. But overall, most are similar—it usually comes down to price, brand name, and the way it personally feels in the hands of the user."

Tempo's Carefoot adds, "Even with simple tools like tones and probes, technology never stands still, and product development never stops." According to Carefoot, the future of tone generators and probes will see more usability-type features, increased reliability, and durability to stand up to the toughest conditions.

"I think people want durability, and they like to know that a tone generator reliably transmits a signal they can easily find," says Carefoot. "People use tones and probes day in and day out for hundreds of applications—you can't pull the wool over their eyes."

Betsy Ziobron is a freelance writer covering the cabling industry.

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