Hello Everyone,

I am very excited to start my Western Electric 1A2 551B KSU project and I have some questions about the 551B KSU. The information that I was able to research, that the KSU was not designed/built for dial selective dial intercom.

Since I only would need 3 lines, can the 4th card slot be used for manual intercom? If so, would I have to do any type of rewiring on the punch down block?

Would you guys recommend the manual intercom card 401A or the 401B card?
Also would any of you have a manual intercom card for sell or would you know a good place to get one? No luck on Ebay…..

Can I add a dial selective dial intercom like Telton or Valcom and use a external punch down block down the road?

Since I will be using manual intercom, how would you wire up the manual buzzer buttons (the small black box with a little white button that attaches to the phone) I think those are (551A SIGNAL KEY) to make the buzzers work from the phone to the KSU. I could not locate any info about that in the Bell System Practices.

Since the KSU does not have a 118A frequency generator ringer and I don’t know if my VOIP lines will have enough ringing voltage to make the phones ring, could you use the buzzers in place of ringers? If so how would you wire the phone or the KSU?

What line cards would you guys recommend to use in this KSU? My ITT 511 KSU seems to like the ITT 400 E cards..

If you guys could let me know a good place or if you want to sell some line cards, a intercom card and some amphenol cables.

Thanks

Do you have this?

http://wedophones.com/TheBellSystem/pdf/bsp/550and551/518-215-407.pdf

It seems like we used the Melko KT-19 but it's probably the ITT 501 I'm thinking of.

Yes I was reviewing the BSP but I think I was reviewing issue 1.

The fourth card slot can certainly be used for a manual intercom. The only thing that card will do is give you a line light and talk battery. There's plenty of spare pairs to use for manual buzzers. A better alternative is a Valcom or Teltone dial intercom. These are separately mounted boxes with (usually) a 25 pair connector on the side that you break out on a 66 block. You give it A, B, and Lamp battery and what ever source you choose to use for signaling. Most of the buzzers out there run on 10VAC lamp battery. Also tip and ring will come out and be multipled to all your sets. They usually don't have a leads, since it can just detect off hook and give you lamp illumination. Not too much need of putting an intercom call on hold since it stays set up even if one person hangs up. It will give you signalling outputs to connect to the buzzers in individual sets. Typically you put the buzzers on yellow/orange or yellow/green. Most sets have the hold lamp on y/g. Just cross connect everything and there you go. (HIGHLY GLOSSED OVER)

You can certainly use the buzzers for common audible ringing. Wherever you would connect the 118A ring gen, you just put lamp battery (assuming 10VAC buzzers) and then put common audible on the yellow/orange pair instead of yellow/slate. (Again, assuming you put your buzzers on y/o.)

Stick with the ITT400E line cards. They are very good and will work with almost any source of dial tone.

If I look I might have a spare intercom add on box..... just have to dig through some dusty boxes. I have a Valcom RT-18 or whatever they called the tone and rotary 18 station model, but I plan on using that. My ITT 501 ksu came with some 10 station intercom box that I think is tone only, but I have to look. If tone only is fine, PM me.

I don't think you have to do any rewiring to use a manual intercom card in slot 4. I know the 551C's had A battery on pins 3&18 for manual intercom cards. I don't remember if you had to change the wiring on a 551B or if it was set up the same... I personally like the add-on boxes because they're dial select. No need to convert pick up keys or have little side cars attached to the phones.

The 401 A required an “A” lead. The 401 B did not.

There may have been an extra relay in the B card that was useful when you used it to access a PA system (to kill the Background Music).

We switched to B’s at some point, but would happily use A’s.

Chris is spot on. The Dial Intercoms give you way more bang for the buck.

I believe slot 4 came premiered with A battery and ground. If not, it was just a jumper on the block to get it working.

You could easily use buzzers. If you want a ring generator, I believe I have a couple in the dreaded basement. I also might have a DICM.

Enjoy! Have fun!

Sam

Another thing I forgot to mention about the dial intercoms. They usually have some audible feedback to the user in the form of a dial tone of sorts and usually a tone indicating signalling. No such joy with the manual intercom cards. You pick up the phone with a manual card and you just hear dead air until someone picks up. The majority of the dial intercoms are a one shot affair as far as signalling. You dial a number and it gives one burst of signal then that's it. They don't usually keep ringing like a normal phone line. Most have the ability to re-signal if it's a touch tone model. I think it's either the star or pound key that will re-signal the called station, often times for as long as you hold the key down. I know my valcom is like that. My personal opinion is I wouldn't waste a card slot in a KSU that only has four slots on a manual card. Might be kind of neat for a private circuit like boss and receptionist or two partners in a law firm kind of deal, but for a general intercom, DICM all the way!

Hi Guys,

Thank you so much for your help. Right now I am just in the beginning stages and my plan in to put my 551B KSU in the den and only use 2 to 3 phones with 3 phone lines.

Would you still have to have a manual intercom card in order to have the dial selective dial intercom with Valcom or any dial selective dial intercom unit? It seems that my ITT 511 KSU requires the manual intercom card to have the Teltone c-19 selective dial intercom to work. I did not build this system, I had a old ma bell tech to build it for me.

I think it would easier for me to get the hang installing and terminating the cables on the touchdown block and get a feel of it before I move on doing a external selective dial intercom unit. Would you guys commander that?? But I still may want a selective dial intercom unit after a get the hang of it.

Did they make different types of buzzers? I think most of my phones have the buzzers with the blue wires.

Do you have to have a frequency generator if I want the buzzers to be the ringers? And also how common was it back then to have buzzers instead of ringers. I think it would be cool have the buzzers as ringers.

Also do you think I might have to a have frequency generator as I might put this behind my Merlin Magix system?

Thanks Brian

Buzzers and Bells BSP

Brian -

One at a time....

- You DO NOT need a manual intercom card to get a DICM working. I'm not sure how this guy built your system, but you shouldn't need a 401. (Also, I think you mean ITT-501, not 511)

- I'm not sure what you mean, Sorry, it's early in the morning.

- I know of at least 4 types of buzzers: Blue wires = 10VAC, white wires = 18VAC, Black wires - 105VAC, Small metal boxes = 24VDC

- Ringers, generally require 90-105VAC. That can be produced by the CO (line bells) or locally by a frequency generator (common bell)

- ?. I'm not sure what you mean.

Enjoy!

Sam

Is the Merlin Magix going to drive the 551B

Sorry for the typo, yes its a ITT 501 KSU.....


Sam: If I remember correctly, the person who built the ITT 501 me said for some reason he was unable to get the teltone unit to work right without the manual intercom card but I could be wrong......


I think I am getting the hang of color code and pins to terminate on the punch down block for the key sets at the top and what needs to be punched down for the incoming phone lines at the bottom of the block.

Only part that I don't understand what color/pins that needs to be terminated for the audible signal part of the punch down block from B1 to CA . As the Bell System Practice that I looked at did not have the color or pin.

If any one has a color chart or a close up photo of the 551B KSU, that would be very helpful.

Thank you all of you for all your help and understanding.

Hi,

Yes most likely it will drive the 551B, it could be a small chance it would be VOIP lines.

If the Magix has a 016T/R module installed it could be used to provide dial tone for the 551 so long as the chosen ports in the Magix are configured to provide ringing voltage, current and waveform that is in line with Bellcore standards. If an ETR module is present, the last six ports can be configured as T/R.

I think I am getting the hang of color code and pins to terminate on the punch down block for the key sets at the top and what needs to be punched down for the incoming phone lines at the bottom of the block.

Only part that I don't understand what color/pins that needs to be terminated for the audible signal part of the punch down block from B1 to CA . As the Bell System Practice that I looked at did not have the color or pin.

If any one has a color chart or a close up photo of the 551B KSU, that would be very helpful.