From: Pat Talbot (talbotpat@xxxxxxxx)
Date: Wed Jan 09 2002 - 23:53:43 GMT-3
High EMI/RFI levels if media filter not used. IEEE 802.5 standard recommends
use of media filter per station to avoid EMI/RFI and for impedance matching.
Traditionally, the Token Ring NIC would have a shielded DB9 connector. In
order to convert over to 4-pair UTP a media filter is required. An media the
150 ohm impedance of the NIC data in and data out circuits with the 100 ohm
impedance of the UTP. In addition, the media filter attenuates frequencies
above 30MHz. Nowadays, most Token Ring NICs present the UTP connection
directly.
----- Original Message -----
From: OWEN, DAN (SWBT) <do7941@sbc.com>
To: 'Phil' <ciscostudent1@yahoo.com.br>; Jonathan Kephart
<Jonathan.Kephart@ind.alcatel.com>; <ccielab@groupstudy.com>
Sent: Wednesday, January 09, 2002 7:49 PM
Subject: RE: Cheap TR Media Filters?
> Fellas,
>
> I have built several DB9(male) to RJ45(female) adapters and haven't had
any
> error problems with them. This will connect a cisco router TR interface
> directly to a TR RJ45 MAU or a TR switch. (Don't plug the token ring into
> an ethernet device - there could be grave consequences!)
>
> Pinouts are:
>
> DB9
>
> \1 2 3 4 5/
> \6 7 8 9/
>
>
> RJ45 (looking into the female jack)
>
> ||||||||||
> |12345678|
> |__|
>
>
> DB9 RJ45
> 1 -- 5
> 5 -- 6
> 6 -- 4
> 9 -- 3
>
>
> This works for me. Let me know what your experience is on this. Anyone
> know why you would need a filter????
>
>
> DanO
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