nanoVNA – that demo board and its U.FL connectors

One of the many nanoVNA cloners makes an interesting little inexpensive demo board with a selection of components, filters etc to develop familiarity with the nanovna.

Above is a pic of the demo board and the supplied jumper cables. The demo board may not include information relevant to using the cables and connectors supplied.

The board uses Hirose U.FL connectors or one of the many compatible clones, and they are causing reports of problems with users.

Above is a pic of the female part crimped on a cable.

The first thing to note is that these are not high endurance connectors, Hirose gives specs for up to 30 mating cycles.

Next, the life if even shorter if they are not mated really carefully. The female needs to be placed quite squarely on the male and held in that attitude as it is pressed home. They are usually quite hard to press on first time, and they MUST NOT be allowed to skew as they are pressed home. There is an expensive special tool, but holding a flat bladed screwdriver behind the female part to maintain orientation as it is pressed home can be quite successful.

There are lots of recipes for extraction, and most are inadequate. Reports of the male part being torn off the PCB show that some heavy handed practice exists. The female part needs to be lifted squarely under the two side tabs and without preventing the body from releasing from the cannelure on the outer of the fixed male part. There is a mid priced special tool, but one can easily be made.

Above is a pic of the smallest size U.FL female part, and the green area shows the shape of a tool to hook under the tabs provided for lifting. The took must fit snugly enough to not fall off one tab, it must not obstruct the body expansion, and it needs to be compact. The tool allows lifting the female part off with force applied to both tabs to hold the connector square to the male part.

Above is a DIY extractor made from an inexpensive (~$3 on eBay) model putty spatula by bending and filing the end to suit.

These connectors are very common on PCBs, used for wireless, GPS antennas etc, and they are on many of the projects described on this site.