I purchased an RF Demo Kit (picture attached) that uses SMA to u.fl cables to attach VNAs to a small circuit board with 18 different circuits on it. When I calibrated my H4 using one cable and using the Short, Open and Load on the PCB, I got the expected results on the 33 ohm, 75 ohm, 3 dB attenuator and 10 dB attenuator across 10 MHz to 1.5 GHz. The attenuators were open on the output side so the return loss was 6 and 20 dB. I didn't try any thru tests.
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