28 Jun
2018
28 Jun
'18
6:14 a.m.
Thinnet is supposed to be grounded at one point, and only one point, as
well. Supposedly that's what the chain on some terminators is for. Some
hubs have a grounding and termination option built in. I don't know offhand
if this was specced in the standard or not. Of course, this often wasn't
followed, or was followed incorrectly and the segment ended up grounded in
multiple spots, which can cause ground loops.
Thanks,
Jonathan
On Thu, Jun 28, 2018 at 4:52 AM, Peter Coghlan via cctalk <
cctalk at classiccmp.org> wrote:
On 2018-06-27 19:34:38 -07:00, Chuck Guzis via cctalk
wrote:
I guess one of the keys to a successful networking technology is that it
should be possible to specify how to install it in a way that people not
familiar with the inner workings of the technology can readily deal with.
There are advantages to keeping the instructions as simple, short and easy
to follow as possible with a minimum of exceptions and special cases.
It might make sense to state that everything should be spaced 2.5m apart
even when there is no advantage to this in the special case of terminators.
The advantage is in reducing the complexity of the instructions. The
disadvantage is it might lead to difficult cases like this one.
On a slightly different point, didn't the thickwire spec call for the outer
conductor of the cable to be earthed at exactly one point, presumably for
safety reasons in case the cable contacted something at high voltage?
This requirement was somehow not carried forward into thinwire, perhaps
because the entirity of a thinwire network, including the connectors was
supposed to be insulated and therefore not a danger to anyone? DEC
produced
insulated thinwire connectors and terminators but other than that I think
this requirement was honoured more in the breach.
Regards,
Peter Coghlan.
On 06/27/2018 04:19 PM, Antonio Carlini via
cctalk wrote:
> No idea. But on thickwire the taps were all supposed to be made at
> specifically marked positions (for the reason given earlier).
> Perhaps someone (incorrectly) thought that the terminator should also
be
at such a
position and so a terminator could not be located at a tap?
It had occurred to me to wonder if some poor tech had measured out, say,
151 meters of cable where 152.5 was called for by the "exactly every
2.5M spec). It would seem that any attempt to add an extra 1.5 was
believed to be called for in order to install a terminator would have
resulted in a "cure" worse than simple adding the terminator at the end
of the cable.