On Mon, Apr 29, 2019 at 10:50 AM, Richard Knoppow wrote:
Where does it show the speed of light in a vacuum? The TDR should be calibrated to the speed of light (electricity) in the cable. For 50 Ohm cable its about 66% of c. Varies with the impedance of the cable. If you know the physical length of the cable you can determine both its impedance and the velocity from it.
On 4/29/2019 1:26 AM, Albert Otten wrote:
Interesting stuff Dennis! I have to look at it in more detail. I consider repeating these tests since I have both Tek cables, though I don't have quality SMA-BNC adapters. Most remarkable is the slow speed of light in vacuum in the USA ;-) Albert
-- Richard Knoppow dickburk@ix.netcom.com WB6KBL
The document says: "The speed of light in a vacuum is 224844343.5 m/Sec= 0.2248m/nSec. " I guess Dennis already used some kind of velocity factor here. But this makes his following derivation invalid: "The Velocity Factor (the speed the signal travels in the dielectric of this cable) is VF = 2* 36.0in * 0.0254m/in * 4.4475nSec/m/9.0nSec ~ 0.90. "
