atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems curious about 1A2

Bill: I did outside plant in the Army in 1978, so I got a lot of exposure to old pole terminals. What I always couldn't understand was that the spare pair was there in the stub, but the terminal still only had 25 pairs and was epoxy-sealed. Where did that extra pair go?

As for the T-screened cable, the extra pairs are provided (one for each 25 pair binder) to provide a talk pair outside of the screened (shield) compartment.

Now, the 26th pair in inside wiring came in handy every once in a while for that fax line when you were afraid to touch that screw-terminal block that had half a dozen two-line phones in five different offices working from it. That nice rolled-up pair sure looked nice.

Don't know where I was when they first started the T-cables, most all the toll was south about 90 miles and I was in maintaince at that time, so other than hearing about it I never worked on any. If I've ever seen a spare in a house cable I don't remember it. Ed, I found two book of the 3 volume set of my old 1A2 manuals, missing the com key stuff, so now maybe from time to time I can look smart too. :toast:

We had another lead on the ringers maybe besides the four. It was used sometimes. What was it for ED?

Oh, good Lord Bob! You guys are making me look old. If you are referring to the blue lead, I am pretty sure it had to do with frequency-selective ringing when used with the appropriate capacitor or maybe tip party/ring party identification. I know it was something like that, but I can't say for sure because it was always taped and stored in any sets I worked on.

Oh, and Bill, I have the Volume 3 (Comkey) manual if you want to borrow it.

Ed,
Kadoos... on the red/white pair.
and yes you are correct about the relays on the interruptor. They had a distinct pattern, you could identify that system unseen from 20 feet away. intercoms were determined by picking tens from one lead and ones on the other.
the tie system even had different taps on the lamp power resistors so that if you added more extensions and the lamps were starting to dim, you just changed the wire tap setting to make them brighter.
do you think it's time to start telling the young pups about frequency selective ringing, party lines and 4 digit dialing?
Tj

Click, click.......click, click, click........click! We could hear it through the floor into the offices above. I knew I was right about the ones and tens because I did a lot of moves and it wasn't one of those deals where you could use a bridging adapter! How about all of those pink/green, dark brown/light brown pairs in the sets? And people thought American 1A2 was complex! Four-wire 1A2 with a completely different color code in the line cord. Now there's a recipe for disaster.

No need to bring up the 4-digit dialing in step offices or frequency-selective ringing for the yung-uns. They might equate that to static vs. dynamic IP addresses!

Quote:
how all of those pink/green, dark brown/light brown pairs in the sets? And people thought American 1A2 was complex!

they never bothered me. The schematics in those days were so detailed, If you knew how to use a meter, it was a pleasure to work on those phones. no surprises.
I saw a lot of those types of color codes on the 50 pair Iwatsu phones. i remember having an issue with the amphenols if they came loose. the return ground for the phone set was in the violet pairs and if the amphenol wasn't screwed tight, it caused all types of problems.
What was the name of that interconnect box that was mandated on all interconnect installations by Ma Bell to isolate their wiring from ours?
TJ

anybody know how 1A2 is used for 911 systems, even today? did a shadow day at my city hall and the IT/phone/audio guy told me that the 911 dispatch still uses some pieces of 1A2 equipment.

Your good Ed we used it for ANI on party lines when both phones were on the same pair.

Jeff: Much of the earlier 911 equipment had the same look and feel of 1A2 mixed with Comkey. The reality is that answering the phone calls in a 911 center can be done from any type of phone. It's the caller information that appears on the operator's computer monitor that really does the work.

Many dispatch centers used (and continue to use) 1A2 consoles manufactured by Plant Equipment, Inc. Their stuff was primarily designed for this type of application and had more flexibility, like conference capabilities.

Most 911 centers now are 100% integrated using a CTI-type package. Still, there are probably many small towns with a couple of rotary-dial 1A2 sets doing a fine job.