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New Member

How do I change vwic-1mft-E1 to balanced?

Hello,

I have a vwic-1mft-E1 in an 1841. I normally use a CAB-E1-RJ45BNC, to convert the unbalanced 75 ohm BNC from the Telco NTU into RJ45 for the vwic, but my customer has said the router rack is many meters from the NTU so I need to use a BNC 75 ohm unbalanced to RJ45 balanced cable (they extend the RJ45 to the rack using internal RJ45 patches, and balanced works for much greater distances than unbalanced)

My questions are:

1. What commands do I use to re-configure the 1841 so that the vwic accepts balanced RJ45, and not unbalanced?

2. Is there a Cisco cable that I can use to convert BNC 75 ohm unbalanced NTU to RJ45 balanced? I looked at the CAB-E1-RJ45TWIN, but it doesn't seem compatible with the NTU (i.e. NTU is 75 ohm BNC unbalanced, and this cable is 120 ohm balanced, and I don't think a twinax cable is physically the right size to connect to the NTU's BNC port).

6 REPLIES
New Member

Re: How do I change vwic-1mft-E1 to balanced?

CAB-E1-RJ45BNC

Also check this document,

http://www.cisco.com/en/US/products/hw/univgate/ps501/products_installation_guide_chapter09186a008007de72.html

it has the pin out and descriptions, please let me know if this works for you?

Gold

Re: How do I change vwic-1mft-E1 to balanced?

I suspect you can do nothing and plug the RJ45 directly into the router.

I do not think there is really such a thing are rj45 unbalanced. The router more than likely only accepts balanced at 120 ohm.

There is a slim chance they are not using 120ohm but unlikely. You can easily get converters.

I have never used a cisco cable to hook up a E1 we always use some form of external balun that does this conversion. Depends on the country and the provider if they provide them or we do.

New Member

Re: How do I change vwic-1mft-E1 to balanced?

Hello, thank you for your replies. Can you please provide the manufacturer/part number of the external balun that you use? Where can I buy one please?

Silver

Re: How do I change vwic-1mft-E1 to balanced?

Hello, you will not need a balun. Using the line-termination command, on the controller, you can change the interface from 75 ohms to 120 ohms. By default, it is on 120 ohms.

See

http://www.cisco.com/en/US/products/sw/iosswrel/ps5014/products_feature_guide09186a00800880e9.html#xtocid2675512

You can use the CAB-E1-RJ45BNC for the 75 ohms unbalanced connection. For 120 ohms balanced, You might need to check the pin connections of your devices and make the cable. You could be lucky that a straight cable will work. The following link shows the pins layout for the card

http://www.cisco.com/en/US/products/hw/routers/ps274/products_tech_note09186a00800b6e0f.shtml#digvoice

Silver

Re: How do I change vwic-1mft-E1 to balanced?

You can also check out the following cables

CAB-E1-RJ45TE

CAB-E1-RJ45NT

CAB-E1-RJ45RJ45

New Member

Re: How do I change vwic-1mft-E1 to balanced?

Hello,

A colleague has told me to use the mt242a-m from black box (link below). The spec seems similar to the CAB-E1-RJ45 from Cisco, but from practical experience the Cisco cable does not handle extending over UTP patch panels between racks, whereas the Black box one does, so there must be a subtle difference in the specifications of each. Thanks to all of you for your help.

http://www.blackbox.co.uk/solutions/display.asp?cs=dvh&id=1&doc=mt242a-m&tx=WAN&sx=G.703/G.704%20Converters

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