Thicknet/10base5 Test Segment: The Cable is In!

[Ethan Dicks]

On Tue, Jun 26, 2018 at 3:07 PM, systems_glitch via cctalk
<cctalk at classiccmp.org> wrote:
> I've confirmed that I now have N connector intrusive taps! These have a N
> female connector on each end, like the leftmost transceiver in this picture:
>
> https://oelzant.priv.at/~aoe/images/galleries/hardware/802_3_transceivers/DSC_0927_med.jpg

Handy.

I'll have to get some pictures this weekend of the stuff I've
collected so far.  I have 1-2 of the ST-500-01 Transceivers with the
non-intrusive taps, and 4-5 of what I am pretty sure now are called
ST-500-02 Transceivers, with a single male BNC sticking up where the
ST-500-01 has the tap "fang".  I'm now thinking for the cost of a few
BNC-to-N couplers (couple of bucks from banggood.com) and a one BNC T
each (of which I have an abundance), it might be cheapest to get the
ST-500-02 acting like an intrusive tap.  It might not meet the spec
for a full-sized network, but for a 15-20m segment, I can't imagine
it's going to break things.  It's probably not a terrible thing to get
some of the cable, cut it into some 5m segments and terminate the ends
with N connectors.  Yes, there will be impedance bumps at every joint,
but I'm not trying to run 100m, just a segment I can set up somewhere
to show how it was once done.

Fortunately, I also have an abundance of DEC and desktop hosts with
15-pin AUI as an option (as well as a 10BaseT hub with an AUI, that's
at the center of my low-speed network at home).

> I seem to recall the CCNA instructor telling us that you weren't really
> supposed to screw a 50 ohm terminator onto an intrusive tap; I don't know
> if there's good reason for it or if it was just a general practice.

I think the reason is you won't have enough distance between the tap
and the endpoint of the transmission line.

-ethan