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open/short offset delay

Question asked by scottrf on Jul 19, 2010
Latest reply on Jul 20, 2010 by Dr_joel
If I do a one port cal on my 8753C (3.5mm), then look at the short calibration standard, and adjust the ELECTRICAL DELAY to make it appear as a dots at zero, the delay is 33.4 psec. This is one half the 16.695 offset delay value indicated in the cal kit.

Question: If I wanted to use a different short as a cal standard, and I "measured" the offset delay by adjusting the ELECTRICAL DELAY until I saw a dot at zero ohms. Would I then use one half that value as the cal kit Offset Delay?

Question 2: Which one is the right delay? I one round trip delay?

I just call-ed with female SMA, so the open (nothing connected) looks like a dot. If I stick on a barrel+bullet (so I still have a female at the end), dial it back to a dot, the delay about 245 psec. Measured length of barrel+bullet is about 26mm. If I figure velocity in PTFE is 70%, then 26mm would be 124 psec, one half of the "dialed delay". So it seems like this "ELECTRICAL DELAY" is twice the electrical delay. Was there a rational for this in developing the 8753 user interface? Seems confusing to me.

Scott Olson