Ethernet cable (Was: Sun3 valuations?)

[Pete Turnbull]

On 23/01/2018 16:48, Grant Taylor via cctalk wrote:
> On 01/23/2018 09:10 AM, Bill Gunshannon via cctalk wrote:
>> If you didn't locate the transceivers on those black marks you would 
>> have had terrible performance as that affects collisions.  Timing 
>> (among other things like grounding) was very important with that 
>> version of ethernet hardware.
> 
> It's my understanding that the marks (black bands or other markings on 
> the sheath) were exactly one wavelength apart.  Which from what I 
> remember ~> understand from my ham radio days is quite important.

No, that's quite wrong.  The marks are every 2.5m (8.2 feet) wich IIRC 
is 1/19th of a wavelength apart, the point being to try to minimise the 
likelihood of connections being made where they'd suffer constructive 
(additive) interference and to prevent transceivers being too close 
together.

-- 
Pete
Pete Turnbull