Acid Lemon


Variable RF Sampler project.


I saw a youtube video from TRXBench describing a simple to build but very useful RF sample probe with a potentiometer to vary the ouput level. This would be very useful for examining your Signal from your HF or other transciever on an oscilloscope, frequency counter, spectrograph, etc.

Basically you just have two SO-239 connectors connected to each other with a strait length of wire which passes through the middle of a toroidal core on which you have 12 turns of wire. From the torroidal inductor you connect a  potentiometer so that you can vary the amount of signal sent to the scope. you can have 100 watts of signal going from your radio to antenna or dummy load and only a small bit of signal will be inductively coupled for measurement. A few pictures will help you visualize.

It is important the pot is a wire wound type as a carbon pot might introduce noise into the signal..


variable sampler sampler circuit
sampler schematic



I used 2 watt resistors but you could probably get by with a little less. You can probably make this from scrap parts you have on hand. The potentiometer was the only thing I had to order.