How to Build a Coaxial Cable Signal Strength Meter

By Alexander Rudinski

Durable and reliable, coaxial cable has been the mainstay for providing homes with cable television since the mid-twentieth century. In today's world of digital television, coaxial cable now sees more use in connecting homes with high-speed cable Internet. These cables are made up of a wound copper core covered by a thick layer of insulation, terminating in a screw-on pin that connects to the female coaxial input on your device. When you have trouble with the cables, the best way to check them is with a signal meter, which is a simple device that you can build at home -- as long as you have some knowledge of electronics.

Step 1

Warm your soldering iron by plugging it in and waiting a few minutes.

Step 2

Lay out the circuit as depicted in the schematic in the References section. As you can see, the circuit requires three capacitors, two op-amps, two resistors, an integrated chip (74HC4040) and 16-gauge wire to connect all the components.

Step 3

Solder all the components together as depicted in the schematic. It is easy to install the components on a bread-board to keep them from shitting and possibly shorting when you move the device.

Step 4

Attach the completed tester to a BNC tee, which will allow you to connect the device to the other components.

Step 5

Connect your oscilloscope to one arm of the BNC tee.

Step 6

Attach the cable under test to the other arm of the BNC tee.

Step 7

Look at the oscilloscope reading. If you see a square waveform, the cable is shorted. If you see a waveform with multiple steps to it, the cable is functioning properly. Refer to the schematic in the References section to see examples of these wave forms.