Review on 📞 Genuine NF816 Subterranean Electrical Telephone by Russ Mashlan

This is version 1.0 of the product and it has some bugs, so be prepared. The instruction manual is a poor translation and seems to have been written by someone who didn't understand the theory behind this device. However, it can certainly serve a purpose. I traced a 50 foot pipe buried about 14 inches deep to within a few inches. I used nylon rope to show the exact path. The trick is knowing which mode to use. The device I have (October 2014) has a 'battery check' which is used to pass current through the cable. The LED lights up when you have a closed circuit. Therefore, directional mode requires a closed circuit with the far end of the cable. A ground loop or large loop of wire is acceptable if the return path is far from the wire of interest. The claimed 3 foot working depth seems correct. I think this will work in automotive wiring since regular steel doesn't seem to interfere with the RF signal. There is also an omnidirectional mode where this device works like a standard toner. For this mode you only need the red cable of the transmitter. If you have a broken wire, this mode can help you find the break.