Measuring is a key part of our hobby. What you can’t measure, you don’t know. This is a list of some test equipment that I have built.
I have tried to keep the circuits in this section as simple as they can be without compromising on their accuraccy. Test gear has to be robust, reliable and accurate. We often confuse between accuracy and precision. For instance, a frequency counter may give you a readdout down to 1 Hz. However, it may be inaccurate if the time base crystal clock is not well calibrated.
Specan: This is an HF range spectrum analyzer with very good performance. It costs 1/10th to build compared to the commercially available spcetrum analyzers