Tuning a diplexer can be challenging. But having all the right tools can make it easier. In this video, we show how three R60 1-port VNAs can be used to measure all three ports of the diplexer simultaneously. This greatly simplifies the tuning procedure which tends to be highly interactive. Alternatively, an affordable TR1300/1 2-port VNA or a 4-port Cobalt C1409 VNA might also be used.