The requisite knowledge does not come in the box

Every so often, I see a post in an online forum setting out a problem along the lines of:

I just put my brand new dool-band vertical up with 100′ of fitted Super400, and connected my brand new analyser and selected measure coax loss and it says my coax loss it 9.2dB. I gotta pull this crap Super400 down and return it to the shop, who can recommend good coax.

For those who don’t know the answer here, the new coax is quite probably good, the failure is in understanding that the measure coax loss function depends on a short circuit or open circuit termination at the far end of the line. CoaxLoss is then calculated as half ReturnLoss, but the method is flawed. You might have to read the analyser instructions to find that that you need a short circuit or open circuit termination at the far end of the line, but they are unlikely to tell you that the method is flawed.

But the wider problem is the readiness of people to try to use something they don’t understand to measure something that is unknown, and then to have such confidence in their own knowledge and skills to take drastic action.