Friday, November 20, 2009

WHAT'S YOUR EXCHANGE?

In the early days of direct dialing, as 7-digit telephone numbers were adopted, Ma Bell decided people would never get used to remembering or dialing such a long string of numbers.

The solution was adopt exchange names for the first two digits; indeed, telephone exchanges were actual physical structures and they were generally referred to by that name. Even now, when the building (probably) houses an all-electronic digital switch instead of banks of electromechanical relays and crossbars, is not limited to a single pair of leading digits in the numbers it serves and may serve ten times as many subscribers, telephone company employees tend to call the locations the old prefix-names.

I knew a few -- Broad Ripple's exchange is CLifford and in WW II, Homeplace/Carmel numbers were VIctory, though I don't know if the exchange on 106th St. had been built at that time. I figured any master list(s) from the telephone companies were long gone.

"Long gone" is not so gone as you might think -- here's the 1955 list of Official Exchange names from AT&T! The Web's enabling of of information packrattery never ceases to amaze me.

UPDATE: Old Grouch points out the use of exchange names-as-numbers dates back at least to six-digit telephone numbers. See Comments

Wednesday, November 18, 2009

DIALTONE, DC AND RINGING: TELEPHONY

I have dialtone and DC on the hotel phone! Not only that, it rings, too, with a nice, distinctive note.

UPDATE: Wired the dial Thursday night. It works but has a little "dial tapping," meaning the bell jangles when the dial is in motion. I suspect this can be solved. It's a telephone!

Started out tonight (Wednesday) polishing the Bakelite front part of transmitter with Flitz (they didn't pay me, I'm just a happy customer) and proceeded to reassemble the entire transmitter: the "cup" or back is held to a nifty pivoting section by two screws through a washer, the "bulldog" style element is held to the cup by four tiny screws around its circumference; that subassembly is fastened to a socket on the front of the telephone with a hollow bolt, flat spring, bendy lockwasher and nut and at each step, you've got to thread the two wires from the element though the next part. It takes about as long to do as to describe and I had time left. H'mm, it's almost a (non-dial) telephone at this point. All it needs is the receiver.
(Note the fine old genuine Spintite nutdriver at the right. They don't make them like that any more, though a nice Klein set comes close*). The inside-the-phone part of the transmitter is at the left side of the upper section. The large silvery thing is the flat spring.

I wired up the receiver (tinsel cord, soft as a shoelace, very nice), connected Tip and Ring of the phone line cord to L1 and L2 terminals in the phone, plugged it in and there was dialtone, loud as life. Clicked the switchook (same as dialing "1") and I was left with DC talk voltage. Reached over to close the phone and it was obvious the transmitter worked, too. Wow! What's next?Talking to yourself, of course. I called my landline number from my celphone and the bell rang! The delay in a modern digital cell connection meant I could get a pretty good idea how the hotel phone sounds, too. It sounds just fine.

Next step is installing and connecting the dial. I have it in place now but I need to get the card in the center properly aligned. The dial is the tricky bit -- I can likely get it to dial but making it properly silence the receiver when it's off the rest position could be interesting.

So, for everyone who was wondering: yes. It definitely is a working telephone.
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* My Spintites are the best from a couple of sets. They used thinner steel than modern ones, which is nice for tight spots but wears out more quickly. Can't buy that kind new so you've got to find them used and evaluate them ruthlessly. This is an absolute affection; Xcelite, Vaco, Craftsman and Klein all make excellent nutdrivers and if the end result is what counts, you should buy a set by one of them. Worn drivers are nothing but trouble.

Monday, November 16, 2009

TELEPHONY, CONTINUED

Disassembled, cleaned, painted (lacquer!) and have begun, slowly, to reassemble the hotel phone. First, a collection of chassis parts -- the things in the center are the back of the transmitter (microphone) and the receiver (earpiece) hook: Basic assembly -- the front of the case is hinged to the back and I have test-fit the network, bell and hookswitch (less hook; it goes in later). Shown with a few of the tools used, including pen-type oiler at far left, used to put one drop of light oil on the hookswitch pivot (funny shading is the lighting, mild orange-peel texture is deliberate):No dial, receiver or transmitter yet. The latter is a whole collection of small parts, most of which I still have to clean and polish. Dial, hookswitch and receiver will be the very last parts fitted.

I did manage to remove and photocopy the schematic. Here's a black & white scan: Click for larger -- I have it larger still and in color for more detail, if anyone else is working on a Kellogg 1155-A or 1157-A telephone.