atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Project 1A2: Phase I complete.

Heck, if he's got 3 pair we can set up a T-1 with a channel bank, I'm sure we can get something working with that - and we'll have 1 pair spare!

Matt - For info on a line concentrator, check out "Concentrator - Identifier" on the web. Here's a sample:
https://www.telephonetribute.com/switches_survey_chapter_13.html

Sam

A line concentrator is a piece of relay equipment that uses one common T&R, plus one control lead per button, (like an "A" lead, but nastier) plus a lamp pair per button, between the set and the equipment. The control lead operates a relay that applies T&R of the associated control circuit's talk path onto the common T&R to the station, and lights the line lamp.

They were used in installations where many multi-line Call Directors or answering turrets were used in a large "square" wiring format, in order to save on copper cabling.

In the list of nightmarish repair assignments, working on a concentrator is up there near the top. Not quite as bad as a crossbar ACD (automatic call distributor.)

Mathematically, the conventional installation would use, as a best case, 2.5X pairs plus a ground, where X is the number of CO lines.

The concentrator uses 1 pair plus 1.5X pairs where X is the number of CO lines.

A 29 button Call Director would therefore use, as a minimum, 72.5 pairs plus a ground.

The same 29 lines on a concentrated tel set would require 43.5 pairs plus a ground.

You can see the how the copper savings would acrue in a large system that had sets with 100 lines or more.

The reason that lamp grounds cannot generally be concentrated is that with long runs of cable, and many lamps lit at the same time, you get a condition known as "cross-modulation" the effect of which is lit lamps will go dim or almost out when other lamps turn on. That makes lit steady lamps look like they're flashing, but in an opposite cadence to the ones that are really flashing. It makes operation of the set difficult. Some systems allow a few lamps per lamp ground lead, to save a few pairs. You can see this condition on the highway at night, when the driver of an old Peugeot turns on the left turn signal, and the rear running light goes out. They were notorious for having a bad ground connection in their tail light assemblies.

But I digress.

OK next question, what is an answering turret?

Ok, It all works.


I would like someone on this board tell me how a crystal am set works without power.

Makes sense, Ed.
Thanks!

A turret is the generic term for several types of large key sets.

Turret? Multi key service apparatus.


Turret? there is no such term.

Line concentrators.. for 1a2? Now that makes you about 80 years old.

The Last time I moved a line concentrated 1A2 unit was At Boston University. That was 20 years ago.

hello

Amplified t-1.. Too short from the co is sent on four wires. to a premise t-1 interface such as tellab or westell ect. To exstend the plug-in

You only need two pair.