Okay, thanks for that description. I'm pleased to hear your standards
are all different lengths to such a degree that it's apparent by visual
inspection. Hope for mine yet, then!
I guess I could check the accuracy of the short and open I fabricate by
reference to the known good 50 ohm standard? For example, say I begin
with the 50 ohm load and calibrate so I get a single spot dead in the
center of the screen.
If I then substitute the short and the open in turn I would expect to
see that spot shift to the far left then the far right edge of the
Smith chart overlay. If it doesn't do so and deviates to any extent
from these ideals across the whole frequency range, then I've screwed
up their construction. Does that make sense?