DSL & Tel filters

[george t. everett]

I have a customer that has just installed DSL for Internet. I have a dedicated line to the modem. The modem came with individual filters for the telephones. My question is can I install one filter a the demark point for the telephones instead of the individual filters?

 

[Dennis Alwon]

I believe you need the filter at every jack where you want a phone. Edit: Well I guess I was wrong. Had a customer tell me you needed one at every jack. The internet provider gave them the the filters.

 

[brantmacga]

I have a customer that has just installed DSL for Internet. I have a dedicated line to the modem. The modem came with individual filters for the telephones. My question is can I install one filter a the demark point for the telephones instead of the individual filters?

yes .................. one at the demark is okay. i've used leviton & suttle; they work fine.

 

[hbiss]

Actually that is the better way to do it because it removes the unnecessary taps and house wiring from the DSL line. It's also good because the customer doesn't have to remember to have filters on all the phones.

If you can't find a "splitter" (what a filter made to be located at the demarc is called which is only a DSL filter in a housing with binding posts), you can make your own. Take one of the phone filters, a couple of surface jacks and a telephone line cord. Connect the filter between the jacks (observe the in and out) and wire the jacks in the line going to the phones. The DSL modem line comes directly off the demarc before the filter.

-Hal

 

[mdshunk]

The Suttle 649A1 is a real handy gadget for splitting out the analog and the DSL right at the entrance or in the phone room, saving the need for a filter on every phone and fax machine.

 

[mdshunk]

The Suttle 649A1 is a real handy gadget for splitting out the analog and the DSL right at the entrance or in the phone room, saving the need for a filter on every phone and fax machine.

 

[Billy_Bob]

FYI - Telephone lines can carry frequencies which we can hear and also frequencies which we can't hear. DSL takes advantage of this and sends its signals using a higher frequency than we can hear.

In the graphic below, you can see that voice uses a lower frequency and DSL uses higher frequencies.

Sometimes cheap home phone equipment is not well designed and might emit frequencies which "stray" into the DSL area. The "filter" only allows the home phone equipment to use the frequency range it is allowed to use. Thus keeping these from interfering with the DSL.

So does not matter if there are filters on each phone/FAX/Caller ID, etc., or one filter at the demark. Either way they will block unwanted signals and keep the DSL frequency range clear. But easier to just install one filter at a main point.

 

[LarryFine]

When we got DSL, I ran a separate home run to the demarc (sorry, Marc), attched it to the incoming pair, and ran the rest of the home-runs through the type of filter-in-a-box (a FIB?) Hal described.

The phone-company installer hadn't seen this done before, and was impressed with the whole idea.

 

[brantmacga]

the telco in my area will actually give you and install one filter at the demarc if you request it; maybe you should call the phone co. george and ask.

 

[george t. everett]

the telco in my area will actually give you and install one filter at the demarc if you request it; maybe you should call the phone co. george and ask.

Thanks, it's worth trying.

 

[hbiss]

Sometimes cheap home phone equipment is not well designed and might emit frequencies which "stray" into the DSL area. The "filter" only allows the home phone equipment to use the frequency range it is allowed to use. Thus keeping these from interfering with the DSL.

Well, that's not exactly true. It's not an interference issue but rather the phones loading down the DSL signal because they exhibit a low impedance at the DSL frequencies which looks like a short. The DSL filter is a low pass filter that blocks the DSL signal from the phone so that it won't be attenuated.

-Hal

 

[ptonsparky]

DSL goes into new shop today. Looks like I better change a wire or two add a jumper and cross my fingers.

Thank you.

 

[Rampage_Rick]

the telco in my area will actually give you and install one filter at the demarc if you request it; maybe you should call the phone co. george and ask.

Ditto up here, though I usually do it myself.

The standard NID protector here is the Siecor PTD-1U1S. Swap it out with a PTD-3L1H-PSSR1 and you're laughing. I have a dozen left over from when I was subbed to install DSL CPE in a chain of supermarkets. My other favorite DSL splitter is the Wilcom PS-15, which works great for backboard and inside wire applications.

 

[don_resqcapt19]

the telco in my area will actually give you and install one filter at the demarc if you request it; maybe you should call the phone co. george and ask.

Here they will do that too...but only for a $150 charge.