Use cal kit standard #5 for sliding load.

If your calibration kit contains a sliding load, you should be aware that some models of the HP 8753 and HP 8720 network analyzer families will only calibrate properly if the sliding load is standard #5. If you assign the sliding load to any other standard number, the calibration will not work - the error corrected data will be grossly wrong in the sliding load's frequency range. Furthermore, on these VNAs standard #5 can only be used as a sliding load - when you attempt to measure #5 during a calibration, the VNA will ask you to "set the slide" no matter how you defined the standard. This problem is corrected in the latest models.