atcomsystems.ca/forum Forums TDM Business Telephone Systems Comdial Telephones & Systems Comdial Off Premises DX80 Station (max length)

Does anyone know the spec for the max distance from the DX80 Control to a digital station? I have a customer that has rented an office three buildings up the street and we would like to put local extensions in the other building. Telco gave us dry copper pairs - distance to other building is about 1500' - Analog station off DX80 works fine, but digital station gives a little initial flash of the display then appears dead. This worked fine for another custer with ATT/Avaya/Lucent Partner system. Does Telco perhaps have an impairment on the line that causes a problem, or just not likely to work with DX80 digital station?

best test is to chicklet 2 boxes of wire together and hang a phone on the end. Doubling up on the pair also helps.

Interestingly enough, the analog station specs are less than the digital. Here they are from the DX-80 manual:

Maximum Cable Length

Digital Key Telephone---24AWG--1416ft 22AWG--1983ft

Analog Telephone---24AWG--1133ft 22AWG--1586ft

This is measured from the phone to the KSU--linear feet.

Marks suggestion of doubling up would seem to be advisable according to the specs.

Yes ... good idea ... I did that last time for the partner system before we ordered the lines, (so I knew it would work) and have also done that for private DSL type modems to test ability to carry network from building to building over leased lines.

If it works on 2000' (two boxes of wire) then it should work on the leased lines and I can press telco to remove impairments (they don't like you to put data over the lines and often give you more than just plain copper), or look for faults.

I would be hesitant extending stations IROB as you describe. Did you try the cordless phones? External antennas may be required.

I had a very similar situation with a DX80 several years ago. The system was going into a sewer plant, which had underground cables put in by Bell after the flood of '72. It was for a 1A2 system. We put in a DX80, and used that cable for the stations. The switch was at one end of the facility, and the office was pretty much at the other end. Wound up with a similar problem on the extensions in the offices.

Had an IST port in there for credit cards, and it worked fine. I had tested the length of the phones working by checking like Mark said, and it worked. As soon as I put it in the house cabling, the digital sets would either not work, have garbled displays, or very poor audio.

The length of the cable when I read it was sort of erratic on different pairs, but since it was originally 1A2, I knew that there were splices in the manholes to feed multiple buildings and locations, but in the 15 years I was servicing their 1A2, never had any problems with the cable. So, down in the manhole I went, and cut off the cable to 2 unused locations. Some of the problems went away, all the phones still would not work.

We moved the switch to the office building, and still no digital service at the end where the switch originally was, but we swapped them to IST sets, and got the sets in the office working. About a year after, they were doing some remodeling, and they buried a new 50 pair cable, voila, digital phones now worked on the other end. Comdial TS thought at the time that due to the bridge taps, that was the problem. Removing those 2 cables, and noting the improvement, sort of suggested they were right.

Anyway, after all that, does your cable really run from building to building, or does it go back to the CO and back again. IST seems to be a little more forgiving. Or could they have not cut the pairs off, resulting in a bridge tap that continues down the cable? I have 3 dry pairs, in a former BELL PA area, that go 2 blocks, but they really go back to the CO. They told me upon installation that that is the only way they will connect them.