I've tried the ECAL and it performs a cal but it certainly isn't any better. It likely needs a cal itself. It is a real struggle to find really good N ECAL units for hobby level pricing. I have excellent 3.5mm ECAL's though

When you say isn't any better, can you plot the Ecal calibrated results (of the Times kit measurement) and the 85032E results on the same plot. It would be interesting to see if the results are both bad in similar ways. And, just for fun, measure the 85032E standards using the calibration from the Ecal.

The question in my mind is whether the Times kit is a bit odd, thus having a response that is not well modeled by the simple polynomial model, or if it all relates back to the reference calkit. But, since I don't see a ripple associated with the cable length (1 m should give a ripple on the order of a couple hundred MHz), then it means the raw source match and directivity of the Fieldfox is being removed.

On the topic of splitting the cal standards: it won't do much good to get a "better match" if the reference data isn't correct. So the thing to determine is if it the Times standards that are unusual, or if it's the reference cal kit. The 3 GHz ripple pattern points to something like a 5 cm length, which I wonder if it is consistent with the actual length of Times kit. If it is, it might be the nominal center conductor impedance is off and so the delay term should have a non-50 ohm result. The fact that the values you obtained has the impedance as

**exactly** 50 ohms seems to indicate to me that the chance that the center-conductor to outer-conductor impedance error is not being considered in the fitting. Otherwise I would expect numbers like 50.00315 or 49.9990; given that you have 9 significant digits on the delay, for example. Maybe you have to fool around a bit with the offset delay value.