sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems very large 1A2 system?

Hi,

About five years ago, I saw what I (suppose) was a very large 1A2 system being removed from a commercial building. By the dust on it, I guess that it had not been used for years. It was in a steel rack cab and had a combination of 1A2 KTU cards, individual relays, terminals and lots of 1A1 looking KTUs. Many of the relays were on individual sockets that were wired with screw terminals. I would hate to have to work on that without complete documentation!

Judging by the size of the building in an old industrial area of kansas city, I would say that there must have been a hundred stations and maybe (?) 10 to 15 lines. The cab was about six feet tall, had a door and the back was covered with terminal strips / amp sockets.

Did WECO make such large systems or was this simply a creation of installers/engineers who just built a larger version of a good thing?

Best,

Joe

My familiarity was with ITT systems, but we could mount a number of their 584C panels to build up a system to just about any size.

Dave is correct.

1A2 (and the former 1A1) systems are scalable, meaning that there is no limit to their size. You just keep adding panels, relays, power units, etc.

I worked at a hospital that had a 1A2 key system that was comprised of around 250 584-panels and 150 or so dial intercom units.

There were about 12,000 telephones.

What you saw might have been a combination 1A1 and 1A2 system, or it might have been a pre-packaged 1A1 system or it might have been a 6A intercom, which provided dial tone, two talking paths, selective ringing, and flashing line lamps. It was about 7 feet tall and mounted in a so-called "Parker rack."

Sounds like a 6A intercom system that could grow quite large. There were a lot of wire spring relays on KTUs (Key Telephone Units), which made this working monster. It was only dual-link, meaning that two parties could talk at one time, but only one with privacy.

Once the connection between two parties was established, the talk path was shifted over to a private channel. The second conversation was not private, meaning that anyone could barge in on the call.

Unlike typical intercoms which shared a common talk path with no privacy, the 6A provided individualized station treatment, flashing lamp on calls, interrupted ringing and even ring back tone. These were all field options that were determined by strapping between screw terminals on the individual KTUs.

The last newly-installed 6A I saw was in 1977 at a very large residence. Before New Jersey Bell had it fired up, the Tone Commander ML-8000 came out and they abandoned its deployment. I guess that a 15" cube for 80 stations vs: a rack full of relays was a no-brainer. The original 6A never came to life, but I'll bet that it is still there in the cabinet.

WECOs all-electronic 6B offered more flexibility, but the architecture was completely different. It was card based and functioned much like today's hybrid key systems.

As for lines/stations, the 6A never addressed line capacities. The only limitations were the number of intercom codes. You could have dozens of lines with no direct relationship to the system itself.

Rack-mounted 1A2 offered literally no limits in capacities and features (those available at the time, of course).

The 6A was perhaps the last step switch-based communications system offered in the Bell System. The call processing part ('processor') was the die-hard 207C selector. Yes, individual KTUs had to be hand-wired in the field and God forbid that a customer exceeded the maximum configuration. That is why they had single-conductor switchboard wire (tinned copper).

All 1A2 equipment that was rack-mounted used standard 23" mountings. For individual KTUs, rails were spanned between the verticals to provide mounting space for them.

We had scalable cabinets. I remember the bigger ones like the 36 with three rows of 12 ktu's that hung on the wall and a "tombstone" that sat on the floor with that started out with around 48 ktu's. At the airport we had racks in bays.

Where would one find a picture of a "Parker rack"? I have looked on google and not come up with anything. Where would one even go to look to acquire something like that?

Joe

Joe,

To assist you, take a trip to Abilene, KS, look at the Eisenhower Museum, walk across the street to the Ford County Museum of Independent Telephony. Very interesting....plus it is a nice weekend get away from KC....and you can see the Greyhound Hall of Fame there, also..... :thumb:

And the KS collegiate athletic museum, or whatever it's called.

I lived in Salina, KS for 10+ years, 25 miles west. Went to the Eisenhower museum once to see an antique car show, didn't even think about going in! And never got around to the Telephony museum either. Only reason I went to the athletic museum was to install their phone system. Heck, I was raised and lived in Kansas city for 40 years, only went to the Truman museum in Independence because my Father-in-law was a BIG Truman fan. Heck, I'm an 'R', why would I go to a 'D' hangout! Odd how you never 'visit the sights' in your hometown.

It is a telephone company internal term. You won't find an image of it anywhere except in the minds of old phone guys. The members of the clubs night have one for sale. Have you joined yet and asked them?

In civilian life, it's what Ed said: a 7-foot tall rack, for mounting 23" equipment. It came with a gray fiberglass cover that was difficult to remove, and impossible to replace.