Labelled caps for OSL calibration loads

thingiverse

Those who rely heavily on Antenna Analysers and similar equipment will find it essential to regularly calibrate them with OSL (Open, Short & Load) terminators. Such devices can be easily crafted from OTS BNC or SMA connectors, but they gain a professional appearance when equipped with a labelled cap. This particular setup consists of three caps: 0 ohm, 50 ohm, and Open Circuit - all designed for use in OSL terminators. Building these terminators is a straightforward process. Begin by cutting off the center pins from each connector. The 0 ohm termination simply involves soldering a wire from the center pin to the body of the connector. In contrast, the Open Circuit termination requires nothing more than cutting the center pin off entirely. The 50 ohm termination can be a bit more challenging. Some individuals have successfully implemented this by soldering two 100 ohm SMD 1206 resistors directly from the center pin to the body of the connector. However, I found this approach to be extremely difficult and prone to failure. Instead, I opted for a simpler solution: soldering two back-to-back resistors and adding flying leads to them. This design allows the resistors to fit comfortably inside the body of the connector.