Duplexers, what are they and how are they tuned?

Tuning a set of cavity filters for a ham radio repeater using the Rigol DSA815-TG spectrum analyser.

Tune a Duplexer with a Spectrum Analyzer + Tracking Generator or VNA

This video shows how to tune a notch-type duplexer using a spectrum analyzer with a tracking generator, as well as with a vector network analyzer (VNA). It also discusses the basics of what a duplexer is and a quick review of the most popular types. The type of duplexer shown in the video is popular for 7.6MHz and 9MHz split amateur radio repeaters.

Can you tune a duplexer with a NanoVNA V2plus4?

An interesting video comparing the results between a relatively inexpensive NanoVNS V2plus4 and a Tektonic TTR506A. He shows you can achieve acceptable results with the less expensive instrument. The NanoVNA V2plus2 has a greater dynamic range than most of the cheap NanoVNA’s which are not really suitable for duplexer tuning.