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@bte
We can also use a very simple device to measure RF voltages (not currents): a simple diode followed by a capacitor, which rectifies the RF voltage. But this only works in one particular case: the signal must be periodic, unmodulated, have a level of at least several volts, and have no DC offset or offset to compensate for. Since what we're measuring is the peak voltage, we also need to know the shape of the signal to obtain the RMS value. If the signal is sine or rectangular, this is easy.
I've often used it to measure RF output voltages from radio transmitters. It's accurate. For better precision, don't forget to add the 0.6v knee voltage to the measurement if the diode is Si.
An oscilloscope measurement doesn't work well at high frequencies, especially if you're using a high-impedance output and a high-impedance ordinary probe. The divider in your diagram with resistors R4/R5, which are very large and probably more or less inductive, will form a low-pass filter with the input capacitance of the probe. In addition, ambient radiation can induce currents directly in the probe, greater than the signal connected to the probe. This will work approximately for a few tens of KHz, but if we're talking MHz, the measurement will be false.
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"Open your mind, but not like a trash bin"
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Author
Topic: Tetra Replication (Read 16367 times)
