nanoVNA-H – continuing USB-C woes

I have reported issue with the USB-C plug / socket arrangement on the nanoVNA-H.

It is very sensitive to any jiggling of the cable or connector, causing a reset of the nanoVNA which almost always means lost work.

Having tried a number of different cables that have worked reliably on other devices, I initially thought there was little difference.

I did have a good response to jetting plug and jack with IPA, but the effects are shortlived.

This brings me to consider whether the connector is degrading making debris that makes for unreliable contact, or whether this is too little spring pressure in the plug.

Above is a view into the supplied USB-C plug. The pic has been taken with care to line up the die parting marks at back and front of the connector, so the view is in line with the connector axes.

First it is obvious that only the bare necessity of pins are populated so an indicator of CHEAP. Functionally though and therefore more importantly, the contacts on the lower side of this connector do not project as far towards the connector midline as the upper contacts. I make the distance from the lower contacts to the midline to be four times that of the upper contacts.

Above is an attempt to measure the distance from the midline to the top of the contacts in the lower side of the jack. Given that the specification thickness of the tongue in the plug is 0.7mm or 0.35mm either side of the midline, contact pressure from these contacts will be low and possibly break with wiggling of the plug.

Cheap Chinese junk.

5 new USB cables were tested and in ALL cases, the connection is much more unreliable with the connector plugged in one way than the other which is a strong hint that the jack is faulty. Visual inspection of the jack does cast some doubt, and despite that it is a difficult repair I intend replacing the jack if / when an order from China arrives, it is a country with serious third world health problems right now and that is disrupting deliveries.

Some users apparently lacking the skills to replace the jack have simply cut the end of the cable and permanently attached the wires to the board. I don’t scoff at that at all, it might wind up being the best solution.

Everything about the nanoVNA-H is a squeeze to keep the price below US$50 without much consideration to performance.

Discussion about the upcoming nanoVNA V2 is likewise centred on selling price which appears to be the prime design criteria, it shapes every aspect of the solution.

It also speaks to the target market, hams, who they think will buy anything that is cheap. Who am I to argue with people who have sold thousands of these things?