I was testing some baluns from my junk box collection to see what types (impedance ratios) they were, using a non inductive resistor and my VNA, since they're just unmarked PVC pipes and I had lost track of what was what.
I found a 4:1 and 9:1 that both behaved reasonably well. Not sure where these came from, I think Buxcomm?
Then I tested what I was pretty sure was a standard 1:1 balun I got at a hamfest. You see them there all the time, the ubiquitous white PVC pipe balun:
Very strange. Here's the SWR plot and impedance plot:
OK, this one is just bad or something. I tested another similar looking balun. Same results. So I tested a third. Same results.
Alright, let's crack one of these open and see how it is made, how many ferrite cores are in it, etc.
Well, that explains why it doesn't work, doesn't it? Just a few turns on a 1" diameter PVC pipe. No cores. My guess is they were aiming for "terrible but not bad enough that the user will know for sure it's the balun and will blame their antenna instead" on 40 and 20 meters. And super terrible everywhere else.
Anyone want to buy a cheap balun?