The Leica Midi Sonde 8/33kHz is a self-powered dual-frequency locating sonde for tracing the position and depth of non-metallic underground pipes, drains, and sewers. Measuring just 38mm (1.5") in diameter, it feeds easily into standard drain and duct systems, broadcasting an electromagnetic signal that a DD-series locator can track from the surface above. With both 8kHz and 33kHz frequencies built into a single unit, the Midi Sonde adapts to varying soil conditions and depth requirements — giving drainage contractors, CCTV inspection crews, and utility surveyors a reliable, versatile locate tool for non-conductive underground infrastructure.
Key Features
Dual Frequency: 8kHz & 33kHz
Select 8kHz for better signal penetration in deeper or high-conductivity soil, or 33kHz for standard utility depth work. Two modes in one compact sonde.
38mm (1.5") Diameter
Sized for standard drain and sewer access. Fits inside residential and commercial drain systems, inspection camera housings, and boring tools.
M10 & 3/8" Thread Adapters
Supplied with both an M10 male thread and a 3/8" adapter — attaches directly to drain rods, boring tools, and inspection camera heads for push-in deployment. Two fittings in the box means it works out of the package on a wider range of equipment.
AA Battery Powered
Runs on a single AA alkaline battery (included). Self-contained — no transmitter or tether cable required. Simple, reliable, ready to go.
Up to 5m Working Depth
Locatable up to 5m (16.5ft) deep. With the DD130 locator, depth estimation is accurate from 0.1m to 9.99m for precise excavation planning.
Drain, Sewer & CCTV Compatible
Works alongside CCTV inspection cameras — locate the camera position from the surface as it travels through the pipe system.
How It Works
The Midi Sonde is a self-contained electronic transmitter inside a ruggedized housing. Here's the workflow:
- Install the battery (1× AA alkaline) and select the frequency (8kHz or 33kHz) for your conditions.
- Attach the sonde to drain rods, a boring tool, or an inspection camera using the included M10 or 3/8" thread adapter.
- Feed the sonde into the drain, sewer, or duct through the nearest access point (manhole, cleanout, etc.).
- Locate from the surface — walk above the pipe route with a DD120 or DD130 locator. The locator picks up the sonde's signal and guides you to its position.
- Measure depth — with the DD130 locator, get accurate depth readings (±0.1m) to plan excavation safely.
- Mark the route and location of any blockages or junctions found during the survey.
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Technical Specifications
| Article Number | 850289 |
| Diameter | 38 mm (1.5") |
| Frequencies | 8 kHz and 33 kHz (dual, selectable) |
| Thread | M10 male + female adapter & 3/8" adapter (both included) |
| Battery | 1 × AA alkaline (included) |
| Max Working Depth | 5 m (16.5 ft) |
| Depth Estimation Range (with DD130) | 0.1 m to 9.99 m |
| Compatible Locators | DD120 (detect only), DD130 (detect + depth), DD300 Connect |
| Compatible Tools | Drain rods, boring tools, CCTV cameras (M10 or 3/8" adapter) |
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Complete DD120 + Midi Sonde plumbers kit — locator and sonde together.
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Art. 872939
Entry-level electromagnetic utility locator for detecting buried cables and pipes.
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