News:

"The phone is a remarkably complex, simple device,
and very rarely ever needs repairs, once you fix them." - Dan/Panther

Main Menu

Markings on ITT 500.

Started by Stephen Furley, August 31, 2011, 06:02:07 PM

Previous topic - Next topic

AE_Collector

Gailsberg Illinois apparently

Terry

GG


The fingerstops themselves varied, but the mounting details of them didn't.  By analogy with the variations on fingerstops on GPO trigger dials with plastic bases, or between those on GPO metal-based trigger dials and those on Australian PMG dials of the same type. 

So what I'm sure you'll find on that ITT set is a #7 dial in which all parts are fully interchangeable with Western Electric, but the fingerstop is slightly different.  That said, there is similar variation within Western Electric. 

Why so many beige ones: 

Mostly because the non-Bell "independent" telcos used them by the boat-load, and beige was a popular color in the US in the 1970s - 80s. 

Also because the interconnect industry used them by the trainload on PBXs in the 1980s.  Back in the day, we went through oodles of those on Ericsson crossbar PBXs; and dialing 1 was the means of producing the "recall register" signal so there was no need for a "ground button."    If you find ITT 500s with dial cards showing extension numbers, they came out of PBXs installed by interconnect companies, usually in Bell territories.


Stephen Furley

I'll have to take a closer look at the dials when I get time.  Do you know much about the GPO metal dials?  The No. 10 has provision to mount the finger stop in an alternative position, similar to where it is on WE dials.  On the WE dials it has to be in that position due to the location of the 0 hole; presumably this was to enable a slightly smaller dial.  I've read about the additional mounting holes on the No. 10 dial, and they are there in the dial in my 1/232, but I've never seen any explanation of their purpose.  If you wanted to convert a GPO dial into something similar to a WE one then you'd need to replace the finger wheel and the pulsing cam, and probably a few other parts as well, in addition to moving the finger stop, and I can't think of any reason why you'd want to do this.  If you simply moved the finger stop then it would be a long way from the 0 hole.  The effect of this would be to reduce the delay between the finger releasing the dial and the first pulse being sent out by a few milliseconds; again, I can't see why you'd want to do this.  Any idea what the purpose of this was?  The facility was removed on the No. 12 dial.

Recall causes me no end of trouble at work.  Most extensions are configured to use earth recall, and the company who maintain our system recommend this with the Mitel 3300.  There are two problems with this; firstly our internal telephone wiring is in a terrible state, not helped by the constant changes to the building, walls being taken down and put up all of the time etc.  In some places it's just not possible to get a good earth, or indeed any earth at all.  In two areas of the main building we have 25 pair voice panels in the comms rooms with telephone service patched through the network cabling, and RJ-45 to BT dongles containing the bell capacitor.  There is no earth provided on the voice panels, so we have to use TB recall here.  The two main models of analogue telephone which we have now in theory support this, but the later ones are junk, the keypads die; we have few of these left now.  The older ones were better, and we still have lots of them in service, but they are getting old now, and I'm having to make one good one out of several to keep them going for another year or two.  Also, TB recall has always been unreliable on these.  We still have a few Statesman sets left, which must now be almost 30 years old, and these still work fine.  We had to withdraw several more a few yeas ago because they were LD only and the voicemail system needs DTMF.  Several of the withdrawn ones are now in my collection.

We're now about 60% IP, with another 5% or so going over tomorrow, and we never have any recall problems with these, just program a Trans/Conf button on the 'phone, and it works every time.

GG


Hi Stephen-

Probably less than you know about GPO #10 dials, seeing as I'm in the US.  However....   Alternate finger-stop mounting:  Slipping cam dials were used in Denmark on KTAS and JYDSK phones, and the fingerstops are mounted on those alternate holes there.  Presumably if one were to look, one would see the cam mounted accordingly to give normal 1-9,0 pulses. 

The reason for allocating more blank space between digits 1 and 0 on a dial, was to give a longer inter-digit pause as the dial returned (between its last pulse and the first pulse of the following digit dialed by the subscriber), to enable Strowger switches to finish their motion and connect to the next switch in the switchtrain.  GPO, German Post, and French PTT were all "conservative" in allocating the equivalent of four finger-holes' worth of blank space for their dials to return, to minimize risk of wrong numbers (and Germany used the Siemens "rotary" system rather than Strowger as such).  KTAS et. al., as well as Netherlands PTT, allocated less blank space: the equivalent of three finger-holes rather than four, between 1 and 0.  Automatic Electric USA, and its foreign associates such as ATEA Belgium, also allocated the equivalent of three finger-holes' worth of space between 1 and 0.

So I'm going to guess that the variation on the base of the No.10 dial was that the Danish telephone administrations felt they didn't need the extra fraction of a second of inter-digit time, and the design for the dial was to enable its use by administrations that made differing choices on inter-digit time.

---

The Bell System adopted Strowger reluctantly until they could design the Panel system.  However they started producing dials at the same time as the other manufacturers (chiefly AE, SC, and Kellogg) were also producing dials with two finger-holes' worth of blank space for shorter inter-digit pauses, so they also produced them that way.  But while AE, SC, and Kellogg eventually moved to all allocate three finger-holes' worth of inter-digit pause, WE kept its dial design externally the same as before.  And the Bell System's preference for interchangeability of parts (despite the change in the dial fingerwheel's center mounting hole) worked in favor of Bell sticking with the same external design of dial that they had started with. 

Re. your problems with wiring:

Eeee-yoww!, that sounds downright terrifying.  That's why my organization insists on maintaining control over cable/wiring & jacks specifications on all our clients' sites.  We have two slang terms for what you have at work:  "spiderweb," when it's just a tangled mess, and "dredlocks" when the tangle has twisted itself together such that it's nearly impossible to untangle.  (The latter is not used in a racist manner, as in the Bay Area California, there are plenty of white kids running around wearing dreds.)

I'm surprised you have so many analog sets in service; what kind of organization are you working for?  I would expect to see lots of analog sets on a college campus, for example, but far fewer in a commercial office environment. 

Yes, IP phones can solve this, as can digital phones (Panasonic DT-3xx series) because the "flash" or "recall register" signal is digital or binary code. 

BTW, do you know where I could find a couple of Plessyphones or Ericsson N-202x phones?  The distinguishing feature of these was that the handset cord comes out of the front of the phone base.  http://www.britishtelephones.com/ericsson/n2020.htm
Most people regard them as cheap and nasty, but I wouldn't mind having a couple (I have one, the PAX version without induction coil; it would be interesting to have the version with induction coil for comparison). 




McHeath

Is the e-bay pic set of the phone you are discussing?  The feet are a little larger than usual, and is it just me or is the left plunger grooved? 

I like the aqua color, pastels were big at various times in North America.  My aqua 500, a WE made unit, is ever so slightly discolored as well, but I've not messed with trying to remove it as it's a very slight problem.