Visual Fault Locator K-V10

• Six powers, one pen: 1 mW for the patch panel and short jumpers, where a stronger light just dazzles; 10 mW as the all-round field version; 15 to 30 mW for long distribution spans, where the light has kilometres of fiber to push through before it can leak out at the fault — same body, same universal connector, the power is the only difference
• Two modes on one slide switch: CW for a steady glow when you are tracing a cord, GLINT pulse at about 2 Hz when several cords glow nearby — the blinking one is yours, and the eye picks a pulse out of a bundle far better than a steady light
• Universal 2.5 mm connector takes FC, SC and ST ferrules directly — the pen walks from the ODF to the floor box to the customer's ONT without adapters; the same pen works on single-mode and multimode fiber
• Reference range runs from about 5 km at 1 mW to about 15 km at 30 mW on a continuous run — covering drop cables, distribution spans and in-building risers, with the exact reach set by the fiber and its losses
• Pen format with a dust cap and a battery LED beside the switch — green in normal operation, red when the two AA batteries run low, so the pen is swapped or re-celled before a trace, not during one: no warm-up, no menu, no manual, and it lives in the tool kit and the shirt pocket
• The classic OTDR companion: an OTDR cannot see the first metres past its own dead zone or tell you which pigtail in a tray is broken — thirty seconds with the pen answers both before the big instrument comes out
• Private labeling made to your requirements — labels with your logo, part numbers and barcodes on the inner boxes and outer cartons, ready for your warehouse

The pen injects bright visible red light — 650 nm, the wavelength the eye is most sensitive to in a dark room — into the fiber. Where the fiber is intact, the light stays inside the core and travels. Where the glass is broken, sharply bent or badly joined, part of that light escapes through the side of the fiber, and because modern jackets and buffer tubes are translucent, the escape shows as a glowing red spot exactly at the fault. No glow at a connector means the loss there is small; a connector lit up like a lantern is the problem.

That is why the VFL is the first instrument out of the kit even when an OTDR is in the van: it answers the practical questions in seconds. Is this jumper continuous? Which of these twelve pigtails is the broken one? Did the drop cable survive the staple gun? Is the fault in this closure or further along? Follow the cord with your eyes; the light goes out or flares at the answer.

Choose the power for the run in front of you. The 1 mW pen is the patch-panel tool: on a two-metre jumper a stronger light adds glare, not information. The 10 mW pen is the general field version, good for drop cables and distribution work. The 15, 20, 25 and 30 mW pens exist for length: light fades as it travels, so on a long span the extra power is what still arrives at a break ten kilometres away with enough left to glow. Use the modes deliberately too — CW for a steady glow at close inspection, GLINT at about two pulses a second to pick your fiber out of a bundle or keep the light visible over distance.

Two habits keep the work safe and the tool alive. Never look into the end of a fiber or into the pen's port while it is on, and never view the output through a magnifier or inspection scope unless it is filtered for it — 10 mW of red laser is not a toy. Mind the battery polarity when you load the cells — reversed batteries leave the pen dead and can damage it. And keep the dust cap on when the pen is in the kit: the universal port's alignment sleeve is the accuracy of the instrument, and grit in it dims every test after.

• One K-V10 visual fault locator (power version as ordered)
• Belt pouch
• Wrist lanyard
• Operation manual
• 2 × AA batteries