Clamp-on RF Current Meter




Here i show a realization of a clamp-on RF ammeter which is very useful to detect a radiation from RF cables or power supply cables due to standing waves.

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Scheme

The scheme is taken from In my case it's composed of an ammeter of 100uA, a PVC case and a ferrite clamp from Wurth Elektronik, 23.7 x 34 x 19mm, ref: 7427113. In case you are using another ferrite the value of the first resistor may change. For this ferrite, the resistor value can be chosen from 5 to 25 ohms depending on the sensitivity you want to achieve.

Step 2: Enclosure Box

Cut out the area for the ammeter in the PVC box and connect the PCB you have made following the scheme in the previous step.

Step 3: Ferrite Clamp

Cut out the area shown on the photo in the case of the ferrite clamp and wound 10 turns of thin wire.

Step 4: Assembling

Solder the PCB wires to the secondary wounding like on photo and you're done. The ferrite clamp can be fixed to the PVC box with a hot glue.


Be the First to Share


    • CNC Contest

      CNC Contest
    • Make it Move

      Make it Move
    • Teacher Contest

      Teacher Contest

    3 Discussions


    2 years ago

    Can this be used to check the signal strength of a RF transmitter?

    2 replies

    Reply 2 years ago

    To check no, since the scale is just an indication, but if you connect two different transmitters to the same radiating cable or a radiating wire (antenna) you can say wich one inject more power.