atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 107A Loudspeaker w/ 565HK

Here it is, in case anyone wanted to see:

1. The REN on the KSU means that it will place that maximum amount of load across any of the four CO T&R pairs. The REN advice is a product of Divestiture, when AT&T equipment, previously installed by the BOC (Bell Operating Company) as part of the whole "System" was considered proprietary equipment, and not subject to the FCC rules that governed "non-Bell" equipment, as used by interconnect companies. When Divestiture occurred on 1-1-1984, the company that would become AT&T-IS (AT&T-Information Systems) became just one more interconnect company, and was forced, (to keep the playing field even) to make all of its equipment conform to the rules that governed everyone else.

That 5.0 REN assumes one 400-type line card, and four line ringers, across any typical CO connection. A REN of 5.0 is the maximum that a CO line is required to power, under the tariffs (government rules.)

2. In a shoebox, you've got a 66 block. The horizontal pins are called ROWS. The vertical COLUMNS are lettered A through F on a B model, and A through E on the C model.

On pins 41 and 42, at the lower RIGHT corner of the 66 block in your KSU, you will find GRD and 18Vac, respectively.

Count backwards (up direction) from the last pin which is 50.

On pins 41 & 42 on the LEFT side of the same block, the pins are spare. Hooray.

Turn the power off (pull the plug, or remove the black fuse thingie) while connecting to those pins, to avoid letting the smoke out.

Do you have a 551 B or a 551 C?

On a "B" version KSU you can just install a pair of bridging clips from 41 & 42 on the right side (column D) over to 41 & 42 on the left side (column C). Then simply punch down a spare pair (the yellow/brown pair is typically used for this) on column A going out to the telephone set.

On a "C" version KSU it ain't so easy, because the morons who designed the C version did something silly on pins 41 & 42 of the left side of the block.

The 66 block has 5 columns. Speaking specifically about pins 41 & 42, column A is connected to column B, but is NOT connected to column C. You need to punch down your telephone power pair on column C. (Do not use column A or column B) THEN put the bridging clip across from column C to column D. Do this on pin 41 (GRD) and on pin 42 (18Vac).

Now GRD and 18Vac will appear on the left side, and you can use them to connect the pair going to your telephone set.

Google "518-215-407 BSP" and when you've got it in front of you, scroll down to the diagrams of the power connections. You'll be able to see what I'm talking about.

A side note: the standard Western Electric telephone had a REN of 1. RBOCS, knowing how many telephones each address was paying for, could test the impedance of a telephone line and determine if the correct number of telephones were connected. If there was a discrepancy, Ma Bell would pay an unannounced visit to check things out.

My dad leased 1 telephone from New England Telephone. The prior owner of the house left a vintage 1957 C/D 500 behind (not sure how that happened back in 1967) in the master bedroom. New England Telephone wired the extension, so the company should have had it documented. My dad removed the ringer assembly and kept the phone. We still have the phone. My dad switched the cord from a four prong to modular. I installed a new ringer several years ago. The handset is amplified and has the thumb wheel.

Yikes, I have a 551C. Looks like this is an endeavour that will have to wait until I get back from my business trip. I will post an update here when I return.

@Paul:

I too find it strange that they forgot the phone. I would think they would be pretty anal about phones considering they were Ma Bell's property...

Thanks all!

is there away to use a 107a as a monitor with a modern pots phone system?

I would like to power it with a 9v dc? can i simply connect the black and yellow to the 9v and then the red and green to the pots two line? is the pots two line the tip and ring?

could i do the same with a 18v ac instead of the 9vdc?

thanks

Go to the whites of the handset don't use DC for an AC application it won't end well.
What's that white bordered square thing with that funny looking thing in front of it in the picture? Yes it's Friday I'm enjoying one of my few days off after putting out fires all week on equipment that nobody is qualified to work on anymore,but me. And I'm a youngster at 53. Oh wait I was in diapers when I started. And probably will be when I retire.

So if I have the 18v ac would I connect that to the black and yellow on the monitor and then the handset wires to the green/red on the handset wires. Thanks

You are correct.

thanks

i have the spokesman working now with a 9v (black and yellow) and an iphone via red/green and the headphone jack - will be trying the telephone soon