FWIW a bit of TDR porn on "finger tight" vs torqued. I think it should be noted that in this example, the ringing is at over 5 GHz, so it really doesn't matter for the current version of the nanoVNA.
This is a little more extreme than most cases, but I often am watching the 11801 while I tighten the connections and see similar results as I switch from the initial finger tight to torqued. Most of the problem is because the SMA hex is so hard to get a grip on. I commonly see such effects disappear while tightening N connections.with my fingers.
I replaced both of the SMA connectors on my nanoVNA with the bulkhead type, so with the connector clamped to a case, the PCB connections won't be strained.
I think a knurled round wrench about the diameter of an N-M would be entirely adequate until you got well above 10 GHz. Perhaps some enterprising merchant will offer some on ebay. Simple to make. Knurl a piece of 2 cm bar, part off, and mill a slot to fit the flats. About $1200 US in tooling and with practice probably 5 minutes to make. I'd buy a well made pair for $10-12 delivered in a heartbeat just for the convenience of not making them myself. So a person in the US should be able to make over $30/hr making and selling them. Pretty good business for someone who is retired and is only looking for play money to buy more toys. I've got the machine tools, so I'll make a pair eventually if no one decides to make them for sale.
Have Fun!
Reg
