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

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C L I C K

I have one of these exact cards that's sitting unused right now, and I'm wondering if there's something I can do with it. First of all, I'm assuming this works somewhat like Step by Step? I'm also judging by the looks of it, it requires an external source for ringing or signaling. Also gathering that this is rotary only, as I don't see anything that would indicate touch-tone compatibility. Is there any way I could use it independently of my 1A2 as sort of an intercom to toy with? Perhaps with a 24V/48V power supply and W/E 118 Frequency Generator? I see it's designed to sit in a card slot on a 1A2 KSU, but nevertheless with schematic of the pinouts this isn't a problem in terms of bypassing using the KSU.


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In addition, while I'm on the subject of 1A2 intercoms... I came across this photo of a phone from the White House that's apparently in a museum somewhere due to it's significance with the moon landing. I noticed, upon reading the labels that the third pickup key is labeled "SIG 190." Any ideas on what that key is for? I'm assuming the SIG is the sig in the word signal, but what about the 190? Is that an extension number? If so, any idea what the White House used for their PBX at this time?

Thanks as always everyone!

Scott

It is a 19 station rotary-only intercom card that can be mounted in the appropriate pre-wired 1A2 or ComKey KSU slot or a 641A modular panel. It's really not going to be of much use to you if you don't have one of the above. There was a touch tone adapter card that paired with it that would also reside in slots in the equipment previously mentioned, It works more like a crossbar switch, meaning that it is a matrix of relay contacts similar to crossbar crosspoints. Any combination of two relays firing creates different code combinations.

I've worked at plenty of government facilities in the DC area and have seen all kinds of button configurations and designations. In many instances, they didn't have people's names or locations to type for the designations, so they would use an identifier such as cable number for the other set. I imagine that this is a non-locking key used in a manual intercom setup. Manual intercom signaling didn't use extension numbers, so they had to come up with some means of identifying stations within the system.

I wasn't aware there were actual Comkey KSUs. Is it just like a 1A2 but with different wiring?

Not exactly. While it is true that the larger ComKey systems used the same line and intercom cards as 1A2, that is where the similarities ended. The phones had similar appearance to 1A2 ten and twenty button sets, but they used an amplified speaker for ring tone and intercom announcements. They also used a different wiring scheme, using two pairs per line appearance rather than the traditional 2.5.

The ComKey 416 had no similarities to 1A2 except for the use of 25 pair cable. There was no actual KSU to speak of, just primary sets that provided line services and power for two lines and one intercom path. Two of these were required to provide a fully-loaded system configuration.

If you want to fool around with a dial intercom that is easy to install and does not require anything more than a 25-pair cable, I suggest a Teltone (or Melco) 10- or 19-station packaged unit.

Most of our discussions about 1A2 on this and other forums usually evolve into a sort of hybrid that involves history and technology. While Western Electric was inventing and producing and distributing their very robust, mil-spec, over-engineered intercom cards (see the Key Systems Manuals or on-line BSP collections for details) the competition was passing them by with the packaged intercoms.

In fact, there was a period at NYTELCO / AT&T when we stocked and provided the "competition's" intercoms, as an expedient. Cheaper, easy to retrofit in older (non 8-inch capable) KSU's, quicker to screw to the wall and run a cable and get the buzz working.

As a 1A2 guy during that period, I was delighted to be able to use them. I had seen them at locations where interconnect companies had installed them, and was impressed with them.

If you Google for "ComKey 2152 KSU" you will probably eventually find the descriptions of the KSU's and all the specialized 4" and 8" cards that go in them.


Getting back to that 2565HK-61 in the White House picture, It seems that there are two lines (line keys 1 & 2) that are extensions off the White House 608B PBX, numbered 500 and 502, and then there is a locking key (number 3) with a manual intercom link. The next two keys, with the names of the criminals Chapin and Halderman, are probably converted to non-locking. Then the additional 4-button pad has what we would assume to be the names of four more of "The President's Men."

Why they labeled the main intercom talk key "190 SIG" is a mystery. Could there possibly have been 190 different manual intercom links? I doubt it. Why didn't the installer just type "ICM" ? In addition, the key is obviously not a signal key, because there would not have been a key available for the talking path. (We discount the assumption that Tricky Dick had a switch hook intercom.)

If the installer wanted to provide -48V instead of -24V for the talking path, he might have used the battery and ground feed from a vacant PBX extension. It might have been # 190. That would have allowed the switchboard operators to have a visual signal that the Boss was on the ICM. That's a wild assumption, of course. It also could have been engineered that way to allow a recording device to get a better signal from the link. "But that would be wrong."

The way it worked was the manual intercom talk key was depressed, and then the appropriate SIG button was pressed. It could be wired in several ways. One way allowed the buzzing to happen, even if the ICM button was NOT depressed first. Another way was to allow the buzzing only if the phone were off the hook, WITH the talk key depressed. It all had to do with what ground lead was accessed by the buttons. The buzzers, by practice, had 18Vac applied to them, waiting for a ground for activation.

There have been many photos, over the years, of presidents' Oval Office telephones. Most of the more modern ones show Call Directors, with the occasional extra 500, 2500, 565, or 2565 (and occasionally even a 3568HAA AutoVoN) set on an adjacent table or at the opposite end of the desk.

Should be -51 Moss Green, not -61 as I typed, by mistake.

I've got two Comkey phones at the moment. One speakerphone satellite and one primary with a red faceplate (which looks awesome). I haven't had much of a look at the internal wiring as I don't want to damage the faceplate of either set. I just bought myself an older IP Office 403 system with some Definity phones online, so I know I'll be setting that up to toy with when I get back. So these projects will be things I'll try down the road.

What's the biggest Comkey setup you guys have seen?

Will the Melco cards provide their own A leads and lamp battery? My gut tells me no, but if there's a way I'm more than confident one of you knows the trick.

Arthur:

I'm glad you mentioned the Melco cards. I do have one of those too. I'm assuming those just need 24 or 48VDC to operate, from a power supply in this case, in lieu of a KSU?

Hookswitch intercom? Is that utilizing the exclusion plunger?

Scott

You can't damage the ComKeys by taking off the faceplates. There's not much to look at, just a back plane with all the parts plugged into special keyed jacks. The largest 1A2-based ComKey that was offered was the 2152. (21 lines, 52 stations.) I worked on a couple that approached those limits.


Be careful. The packaged intercoms use -24 ONLY. NOT -48.

They require filtered -24 A for talk, unfiltered -24 B for signal (relays) 10Vac for lamps, and 18Vac for buzzers. These are supplied from the power unit already in place feeding the 1A2 stuff. Or you can use a separate power unit. Zupp-2-U.

Exactly: Switch-hook intercom is a set of contacts inside the phone, operated by pulling up the left (white) plunger. The contacts do stuff like operating a relay, or switching T & R of a manual or dial icm directly. When you hang up, the contacts restore.

What exactly is the difference between -24V and 24V?

48 volts if this is a math quiz :-)

In Telephony, it's the way equipment is fed because of positive ground.

Carl