So then we're in agreement that screwing the N terminator directly to an intrusive tap shouldn't make a difference? No need for a jumper off the end of the tap for the terminator to live on?
As a high school CCNA hopeful, I accepted this as, "it's what you do," and I hadn't really given it any thought since then, as I hadn't had to mess with thicknet since then. I agree that it doesn't really make sense when you actually *think* about it, and, like I said to start with, it's what I recall being told back then anyway -- I could be remembering wrong to start with :) Thanks, Jonathan On Tue, Jun 26, 2018 at 8:02 PM, Paul Koning via cctalk < cctalk@classiccmp.org> wrote: > > > > On Jun 26, 2018, at 7:20 PM, Eric Smith via cctalk < > cctalk@classiccmp.org> wrote: > > > > On Tue, Jun 26, 2018 at 4:37 PM, Chuck Guzis via cctalk < > > cctalk@classiccmp.org> wrote: > > > >> On 06/26/2018 03:15 PM, Grant Taylor via cctalk wrote: > >> > >>> I can only guess that having a terminator too close interferes with or > >>> weakens the signal too much in some way. > >> > >> Exactly what would the effect be? I recall putting terminators on > >> 10base2 coax just hanging off one leg of a BNC tee. Really, no distance > >> at all. Didn't seem to affect speed or distance. > > > > > > If the termination resistance matches the characteristic impedance of the > > cable, there should be no difference. When terminated properly, there is > no > > reflection from the terminator, so it looks equivalent to an infinitely > > long cable, though in practical terms with less leakage than an "actual" > > infinitely long cable would have. > > > > Of course, in reality it will never be terminated perfectly, so there > will > > always be a small reflection, which can be seen with a TDR. If the > > termination resistance is pretty close, the reflection will be small > enough > > not to matter at all for Ethernet. > > Exactly. And the specs for the Ethernet terminator are quite tight for > that reason. The connectors themselves have non-zero impact but very > small; they are high quality microwave grade connectors. > > You got the definition precisely correct: a terminator is a device that is > electrically equivalent to an infinite length cable. You can cut the > unused part of a coax anywhere you want and put a terminator at that point > instead, and as far as the rest of the cable is concerned nothing has > changed (apart from very small effects because the components are not > perfect). > > There clearly is confusion about what terminators are and how they work. > It's all perfectly straightforward elementary classic E & M, and any > halfway decent RF theory textbook will make things clear. Even a source as > elementary as the ARRL Radio Amateur Handbook will serve. > > paul > > >
