26 Jun
2018
26 Jun
'18
12:07 p.m.
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/D…
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. In any
case, I've got 40 of the things now, which makes a lot of the existing
transceiver surplus (usually missing the tap) useful again!
Thanks,
Jonathan
On Tue, Jun 26, 2018 at 2:50 PM, systems_glitch <systems.glitch at gmail.com>
wrote:
Indeed, the AMP coring tool is more a cutter than a
drill, and it doesn't
go all the way to the center conductor, which would short out the segment
as the cutter is metallic. It doesn't screw in though, it has a shoulder
that stops on the seating surface of the vampire tap body. I don't know if
this is consistent with the original 3 mbit Ethernet, as I've never worked
with that.
The "stinger" contact gets screwed into the threaded hole in the vampire
tap body. Some AMP literature refers to the stinger as being spring loaded,
but none of mine are, and I don't think any of the ones from CCNA days were
either. The shaft of the stinger contact is insulated, only the very tip is
bare. The tip is finished in a sharp conical point, which penetrates the
last little bit of the foamed dielectric and actually makes contact with
the center conductor. I don't know how far it penetrates into the copper, I
suspect it just displaces a small divot around itself.
Cutting/coring is absolutely necessary to get through the quad shield
ground layer on real Belden 9880 or 89880 Ethernet coax. It's tough stuff.
I have to comb out the outer braid and cut the first foil layer to get the
inner braid to open enough for the N connector to seat!
In case anyone was wondering about the color and designation, the yellow
coax is typically Belden 9880 and is non-plenum, whereas the orange stuff I
have is Belden 89880 plenum rated cable.
If I had better video-recording equipment, I'd make a video of the N
connector crimping and tap installation process. I think it'd be easier to
demonstrate that way.
Thanks,
Jonathan
On Tue, Jun 26, 2018 at 2:37 PM, Noel Chiappa via cctalk <
cctalk at classiccmp.org> wrote:
From:
Paul Koning
I believe the original concept was just a probe
that would poke
through
the cable to contact the center connector. The
drill came because
the
cable was too tough to penetrate without it.
No, the original 3 Mbit Ethernet also used a 'drill' (actually, a
cylindrical
cutter which screwed into the thread of the tap housing; threading which
was
then used to screw in the transceiver).
Anyway, there has to be a hole cut _through_ the cylindrical ground layer
(foil, or woven wire) around the center conductor. If you just stuck a
probe
into the cable to the center conductor, it would short it out.
Noel