Good day to all of you! I haven't been on this thread for years after I installed my Mitel SX-50 to power my old rotary phones throughout the house, but have finally started to install my old 1A2 Key system. I will post pictures of what I have shortly, and some fun Autovon stuff I have, too!

I have a general question about the 401A, and haven't really been able to find an answer. Can it be used to connect to an external PA speaker? So when button is depressed, you can have a public address? I have an external amplifier/speaker that has a 'phone line' connection on the back of it, so was wondering if that would do the trick. I attempted it, but could not get it to work. I thought maybe I could barely hear something, but I did notice that with the 401A card installed and the jumps made (1,3,5,7,9,11,43/2,4,6,8,10,12,44) as per manual, that I was able to hear myself through the telephone handset earpiece, when a normal 400D card you wouldn't.

I am in no way an expert; quite the novice. But I love to learn, try to figure things out, and try to do as much reading as possible. Taking it all in--there's lots of experience here!! Any general info/guidance much appreciated.

-Bob Hull

Hi,

Not a expert on this but you may not have enough voltage on the line. I did try a blue tooth speaker with a aux input and I hooked it up on the Tip and Ring and it work okay on my 401 card. I do have a Melco KA-390 Direct Paging Access unit if you are interested as I can let it go dirt cheap. This unit will let you page from a dedicated button to a external amplifier/speaker. I have no use for it as I don;t have enough buttons on my sets.

Hi there, yes I'd be interested for sure, and thanks for the info. I guess I'm having a difficult time figuring out then how the 401A card is actually intended to be wired. I have read many of the BSPs on it, and it still seems fuzzy to me. Like 'connect this to this for this outcome' kind of thing would be helpful to wrap my head around it all.

Also, the amplifier I'm using was previously used on a phone system with a phone connection on the reverse. I remember it working in the building where I work before everything switched to VOIP. It has two phone terminal screws on the back 600 ohm. I was just wondering if I was missing a step in the whole thing before I started racking my brain over it.

Hey Bob, What KSU are you using the 401c card in? Some KSUs like the WECO 551 required the 401 intercom card to be on the last card slot.

The 401A is a manual intercom card that basically just feeds battery to a T/R line appearance on your phones. If one station user presses their (intercom) button and another presses their button they can converse. As I recall, the 401A provides lamp supervision to light the intercom buttons when the intercom talk path is in use, but I could be wrong. There is no signaling. Normally you would have to set up a manual buzzer system to alert another extension to pick up.

So the T/R from that card is designed to connect to the T/R on a phone. Audio with 48 VDC battery. Not meant to connect to an amp to provide paging. It would probably do something if you use an amp with a mic input, but if there is no DC isolation you could damage the amp.

What you need is an ATA like a Valcom-V2000 (T/R in, audio out) or that Melco KA-390. Actually, if you use the Valcom you can just use another 400 line card because the Valcom can be connected to a trunk as well.

-Hal

That's great info, Hal. Much appreciated. So the amp I hooked up to was designed (or at least installed) in a phone/paging environment previously. It's a Precision Electronics ST100E 4-input channel mixer amplifier, with 2 mic inputs, 2 aux, 1-600 ohm Tel/Page. The Tel Page works off one of the mic inputs as I understand, and the paperwork says that the XLR mic connectors are built-in isolation transformer inputs. Is that what you meant about isolation? Could I use just a regular 400D card on this if it's just reading a 'phone' signal, and maybe not need the 401A card?

Here's what I have:

http://cdn-docs.av-iq.com/dataSheet//STE100.pdf

You need connect the 401 card to a WMT-1 (or similar) matching transformer. The 401 card is designed to connect to a 600 ohm telephone line. An auxiliary input on an amp is 15,000 ohms and a mic input is 150 ohms.

They don't play well together without a matching transformer.


Sam

Hi Sam. The back of the amplifier has a spot for 600 ohm phone line. It’s marked “phone line 600 ohm”. Does the 401a card have to be the last card? This is in a smaller 6-card unit

In some KSUs like the 551 A and B's yes it needs to be on the last card slot. Some 551 C's the 401 card can be in any slot. Below is from 551 BSP 518·215-407 .


Manual Intercom
3.11 This feature is provided by installing a 401A
KTU in the KSU. In early production models
of the 550/551C KSUs, only jack J4 was factory-wired
with the talk (A) battery and ground required for
operation of the 401A. Later models (indicated by
an asterisk [*] stamped after the code on the KSU)
are wired to accept a 401A KTU in any of the
four jacks.


3.12 The early models can be modified to accept
a 401A in another jack by disconnecting the
green wires from terminals 3 (A grd) and 18 (A
bat) of J4 on the back of the KSU, and transferring
them to the same terminals of the desired jack.
3.13 On the 550/551A and B KSUs (MD), the
talk battery terminals are factory-wired at
each KTU jack, but only the BR-W/W-BR pair on
J4 is wired back to the talk battery terminals on
the connecting block. The pairs from the other
jacks are dead dressed. To use a jack other than J4 for the manual intercom KTU, disconnect the
BR-W/W-BR pair from the back of the connecting
block, and connect the pair from the other jack
as shown in Table B. Insulate and store the
disconnected pair.

What more phones said.

Also, you could try attaching T/R from the 401card directly to the 600 ohm input. See if it works... It might have a matching transformer built in.

Sam

I'm going to second that you DO NOT want to send your intercom's tip and ring directly into ANY input of an amplifier. Although the intercom talk path is fed by the KSU's "A" filtered talk battery @24 volts, DC, it is still going to be upward of 10-12 volts when a station is off-hook. You'll fry the paging amplifier's input port in no time.

The 600 Ohm input on a paging amp is not designed for anything over 2-3 volts. It "sounds" like it might work on a telephone line because 600 ohms is often mentioned in telecommunications dialog, but ohms and voltages are two different vegetables.

If you can find an ITT 401-PA card, this will give you what you are really seeking.

Aside from a 401-PA card, as others have said, you can use a standard 400 series CO line card in conjunction with any industry-standard external paging adapter, such as those made by Melco, Valcom, Viking or Cooper/Wheelock. These will provide the proper talk battery feed needed to interface with a standard line card and couple it safely to an amplifier.

The WMT-1 is going to kill the battery on the T/R that you need to supply the phones that you need to page from. There needs to be an isolation cap to block the DC. If you look at the Melco KA-390 schematic, it's basically a transformer and it has a cap in series with one side of the T/R input.

I suspect that the 600 ohm amp input will have the same problem.

-Hal

Thanks for everyone's help in this. I gathered that what I was trying to do isn't going to do what I had hoped. I going to get a Melco KA-390 and I think that'll be exactly what I need.

Ed, would a University Sound TM-2 (with a power supply/cap wired in like you had me do years ago) work? I have several extras.

Sure, that would work, Jeff. It might be more trouble than to just use a packaged paging adapter like the Melco unit mentioned earlier. It basically does the same thing when coupled with a filtered DC power supply and a blocking capacitor.

Hi, I have the same issue, looking for a simple way to connect an unused line button (locking screw removed) from a key set to a PagePac Amplicenter.

I came across this Valcom product and was wondering if this would work (I found others, but they required you to dial # or an unused intercom number to connect to amplifier). PAGEPAL® V-5335700 (https://www.pagepac.com/pdfs/pagepal.pdf) .

The installation guide says "(SA) Station Access Used with a standard (ANALOG) station port on a CENTREX, PBX, Key System or Central Office subscriber line. Use a two-wire RJ11 cable in this mode. The PagePal receives talk battery and ring voltage from the host system". Thought I could connect to the manual intercom card. Any thoughts if this will work?

I just found some on Amazon and another vendor, around $525.00 - seems pricey!

After more researching, looks like the Melco KA-390 is the best option... Now to find one! I remember reading there was a WE KTU for paging, but never found the BSPs. Anyone know anything about this? I only need for 4 inside speakers for my home. Thanks!!

You can always scroll through here to see if anything suits your needs:

https://www.telephonecollectors.inf...paging-ktus-1985-brochure-practices/file

THIS WILL DO EVERYTHING YOU NEED and then some. You don't even need an intercom card in order to use it; just wire the line key's tip/ring to this unit and let 'er rip. It even comes with one paging horn. Give this manual a look and if you like it, it's readily available through Viking's on-line store or many other sources.

Thanks Ed, I read up on the specs; there is one item I'm trying to avoid, which is to dial a code before making the page. This unit requires a user to dial 1 first. My system is for a residence, where I want anyone to push the button on the phone that says 'Page' and speak. From what I read the University Sound TM-2 specs connect the phone's T&R to the paging system, nothing else required. I'm still researching - who knew anything could be so complicated! Thanks for finding the Viking PA-2A.

As the instruction on the PA-2A says:

"When interfacing with an unused telephone line input (trunk port), the TALK BATTERY switch (DIP switch 4) must be
ON and the PA-2A must be connected to an unused trunk port. Simply access that trunk port and talk into the handset
to page. A page alert tone may be enabled or disabled with DIP switch 3. When the page alert tone is enabled, paging
will interrupt and hold off loud ringing for the duration of the page."

I have have installed a few of these in my time where a Bogen or Valcom setup was overkill.

True. There's absolutely no way that this Viking unit is able to respond to DTMF tones at all. I didn't see the requirement to dial a digit in the documentation anywhere. Speaking from experience in installing these, they will do exactly what you're seeking from a locking (or non-locking) line key without the need for a line card, intercom card or even a slot for that matter. It provides the talk battery feed and amplification in one tiny little unit.

Nice find, Ed!

Viking never ceases to amaze me with their quality.

Sam

AND, they make some pretty neat gadgets for those situations where you "just need one more feature".

Like a CL-A16 that used 915 – 928 MHz frequency hopping technology!