sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Ringdown lines

Hello all. I am new to this forum, but I am pleasantly surprised that there are still a bunch of 1A2 junkies out there like myself. It's been a while since I installed any "new" 1A2 gear, but I still like to play around with these systems. It always amazes me to see the engineering that went into these electro-mechanical systems long before electronics was used.

I am looking for some help in locating a ringdown module to use with a 1A2 key system. I collect old fire alarm boxes, I and am going to wire up a display using a Western Electric 570 call box telephone and an old 1A2 key system. I would like to use 105 VAC signaling. I work in a large health care facility that used to be heavily 1A2 systems, and the phone guys here tell me that I should use a San/Bar 4415. I know that Viking makes a more modern ringdown module, but this is not really vintage. I would like to try and use authentic key system equipment from "back in the day."

Does anyone know where I might be able to find one of these? I found an electronics surplus store that has a pair, but he wants $135 each for them. I think that's a little pricey especially since he fished them out of a dumpster.

The San Bar 4415 is a standalone automatic ringdown unit that can be used with or without a 1A2 system. It is about the size of a trade paperback and can be rack mounted or wall mounted.

Only 1 unit is needed! To hook it up to a 1A2 system, you'll need a 400 type card on that end. The callbox just gets T&R.

You will need a Power Supply that puts out Filtered -24Vdc (A Battery) and +/-105 VAC (Ring Generator. Filtered power is very important, if not the circuit will have a hum on it. If you're connecting it to a working 1A2 system that's no problem, the power pack should have those voltages. (A shoebox will probably NOT have ring generator, but separate powers supplies are available.)

There is a distance limitation on these units and I don't remember what it is but I believe it's at least 1,000', maybe more.

I have two at home, one is brand new (old stock). If you're interested PM me with an offer.

I believe ITT/WE/AE also made a 1A2 circuit board (461 maybe?) that plugged into a 584c panel and went out to a single line set, but the SL side might have been manual ringdown, not automatic. I don't have one of those, but some of the guys here might.

Sam

If they work properly, $135 is a fair price.
Be advised that a lot of them have one-way failure, in other words, they will not ring in one direction. I have never had the inclination to delve into the circuitry to find out why.

The 461 KTU is a manual ring-down circuit, requiring a pushbutton to activate.

Thanks for the information. Silversam I will contact you by PM about these. I have some 415 ringdown line cards, but this unit seems to be a better solution. I have several shoebox KSUs (one even has the ring generator), and some 20B2 power supplies so I should be in good shape.

I reality I only need to ring in one direction - from the call box to the phone system - since most of these call box systems we set up for placing calls only.

The 415 will require a ksu & card at each end of the circuit. They are very nice units and worked real well. The only problem we had with them is when the Phone Company converted all our ringdown circuits from Copper to T-Carrier over one weekend. We came in Monday morning and nothing worked.

Sam

If you have two 415's, put them in the same shoebox, wired "back to back" and you'll get the same result as a 4415. You will need to add the "A" talk battery to the slots where you install them. The first two slots have it factory-wired, the second two slots do not.

So in the grand scheme, how much more than $100 did you spend to get a 2-way ringdown as opposed to a DLE-200 and a pair of 400 type cards?

Authentic my butt. No Ring Generator, No special cards, just a pair of 400 cards, the ring matrix and you're done.


Carl

Arthur -

Good call! As long as the loop resistance is within spec that'll work fine.

Sam

I will try this with the 415's. For some reason I thought that they could only be used to ring a DC buzzer (not a mechanical bell using an AC ring generator.)

Give it a try. Make sure you have "A" Battery on pins 3 & 18. They are definitely designed to ring 105V bells. Let us know how it works out.

Sam