Re: Insertion delay needed for BNC-BNC couplers UG491A/U (M-M) and UG914/U (F-F)

David Feldman

Now looking at the diagrams on Page 4. The right figure (female BNC) shows reference plane is 0.327-0.335 inches "back" from the outer edge of the female connector.

I'm trying to understand, so please bear with (and correct) me --- I gather that at ~3 pSec/mm, the physical distance between the BNC short "short" position (where the center conductor meets the shield) and the BNC female reference plane position would be based on a one-way delay of 113.5/2 = 56.75 pSec, then the distance would be 56.75/3 = 18.92mm (about 0.75 inch). Looking at the Page 4 drawing female connector dimensions, the distance from the reference plane to the outer edge of the female connector is given as 0.327-0.335 inch, so 0.75 inch is a bit over double (that is, way out beyond the outer edge of the female connector.) Yet when I look at a BNC male short, there is very little metal beyond the outer edge of the female connector until the back edge of the BNC male short's body, so I can't visualize how the 0.75 inch one-way electrical distance fits with this.

In any event, why is delay given as a negative number? If I were to consider the male offset short from HP 85033D calibration kit, the (one-way) offset delay for that component is specified by HP as about 31.8 or 31.9 pSec (I don't have the exact number in front of me - Dr. Kirkby I'm sure would know). Why is that delay specified as a positive value (i.e., what one would enter into an HP 8753 that had no existing standards data for the component?)

Thanks for your patience and corrective efforts!


Join to automatically receive all group messages.