I'm running HPVEE to calibrate these units. Lately I've been getting a lot of failures at the top end of the frequency (over 25Ghz). By a lot of failures I mean multiple units failing in what looks like the same pattern and almost the same values. I've verified the failures manually with different test equipment (different power meter and sensor). I guess my question is, is this a common thing with these units? I've searched around the web for a bit and haven't come up with anything really. I haven't opened them up because the place I work at doesn't generally do repair work and a lot of customers just end up sending them to Agilent. Here are some screen shots from one unit. Band 3 and 4 look pretty much identical on 4 different units so far. And another from a different customer. Any thoughts??