[SI-LIST] Re: cat 6 RJ45 jack for PCB

Jan,

I apologize if I am restating the obvious, but are you sure that your
colleague is even using twisted pairs within the cable?

By this, what I mean is that I have seen 'pin out' errors before, for
example where CAT-5 and CAT-3 have been confused, and when identical looking
(yet different) connectors were used, the result was that in some cases the
two connections for a differential pair were not connected as a twisted pair
within the cable, but rather used one wire each of two different twisted
pairs.

JaMi


----- Original Message ----- 
From: <jan.vercammen1@xxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Friday, June 23, 2006 2:48 AM
Subject: [SI-LIST] cat 6 RJ45 jack for PCB


> si-list,
>
> I have a colleague who experiences problems with 660Mbit/s LVDS on a cat 6
> S/STP
> cable (stranded coaxial overall shield, differential pairs are foil
> shielded). The cable is
> but 3m long. This LVDS chain is used in an industrial machine.
>
> One observes: works-->some bit-errors-->receiver cannot lock (for about
> 500-1000ns)-->
> relock but some -->bit errors-->works. The errors hard to or impossible to
> reproduce on a test bench
> and they seem to occur at random.
>
> We do not know the cause but we are trying to improve the quality of the
> LVDS chain,
>
> We use SER/DES 921224/921023 and they are terminated in 100ohm
> (differentially). Crosstalk
> measurements have not been performed.
>
> After checking the connector we found it to be cat 5, it is specified for
> NEXT to only 100MHz.
> The connector NEXT is much worse than the cable next, for example cable
> NEXT is
> 90dB at 100MHz but only 40dB for the connector.
>
> Because the cable contains both transmit and receive we wonder if we need
> to improve
> the connector. Currently we are using a Tyco RJ45 connector (partnumber
> 406549-1), which
> is cat 5.
>
> I searched the web but I find a large number of dstributors and Tyco does
> not seem to
> offer cat 6 RJ 45 PCB jacks.
>
>
> My questions:
> -1- are category 6 PCB mounted RJ45 jacks common?
> -2- manufacturers??
> -3- any experience to share?
>
> Thank you in advance,
>
>
> Jan Vercammen
> EMC/Signal Integrity Engineer
>
>
>
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