Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!sunic!maxim!prc
From: prc@erbe.se (Robert Claeson)
Newsgroups: comp.dcom.lans
Subject: Re: Req For Info - Ethernet Electrical Rules/Specs
Message-ID: <850@maxim.erbe.se>
Date: 7 Oct 89 00:15:37 GMT
References: <188.2526de30@acci.com> <580@trwind.UUCP>
Reply-To: prc@erbe.se (Robert Claeson)
Organization: ERBE DATA AB, Jarfalla, Sweden
Lines: 24

In article <580@trwind.UUCP> johng@trwind.UUCP (John Greene) writes:
>In article <188.2526de30@acci.com> ta2@acci.com writes:

>>2) Is is legal to run a pigtail of two or three feet from the
>>   base of the BNC T to the Ethernet card?

>This is a definite no-no.  Not only would you be radiating all over the place
>(an FCC taboo) but you would cause an even more severe mis-match than if you
>used a 75 ohm cable.  The impedance of the pigtail will depend on the thickness
>of the conductors and the distance between them.  The cards would probably not
>work with a pigtail an inch long let alone two or three feet.

I've actually seen this, and it worked. The site put a thin ethernet segment
in the walls and had the base end of the T connector going out of the wall.
When there were a need to connect a workstation, a Mac or whatever to the
network, they just connected a few meter long cable to the T connector and
to the thin ethernet connector on the Ethernet board in the machine.

Judging from prior knowledge, this just should't work, yet still it does.
Can anyone explain this?

-- 
          Robert Claeson      E-mail: rclaeson@erbe.se
	  ERBE DATA AB