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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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11th Jan 2015, 12:40 am | #1 |
Pentode
Join Date: Oct 2014
Location: Spalding, Lincolnshire, UK.
Posts: 181
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BT exchange modules from NATO command bunker!
We recently acquired a number of modules from a BT exchange rack in a derelict hardened NATO (USAFE) bunker. They probably date from the late 70s when the building was commissioned.
There were about 10 of these modules in the rack, there were a number of different units in there too but unfortunately I only got these. Not sure who they are made by but they have a TMC label on, they contain PYE and STC components. The valves is made by Standard Telephones and Cables too, it's a fairly common type - 16STE AKA L102/2K. |
11th Jan 2015, 1:18 am | #2 |
Hexode
Join Date: Jul 2007
Location: Edinburgh, UK.
Posts: 344
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Re: BT exchange modules from NATO command bunker!
Seeing the +/_ 80V markings I think these are likely to be voice frequency telegraph units.
A number of these would be frequency division multiplexed onto one voice channel, allowing a number of telegraph or teleprinters to work independently over one voice circuit. |
11th Jan 2015, 1:36 am | #3 |
Pentode
Join Date: Oct 2014
Location: Spalding, Lincolnshire, UK.
Posts: 181
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Re: BT exchange modules from NATO command bunker!
That makes sense. There were about 12 of these units in the rack.
It was difficult to work out what was what - there was an Autovon exchange in there as well so it was all very confusing. Never seen so much comms equipment in one place, and that was after a lot of it had been removed... |
11th Jan 2015, 12:23 pm | #4 |
Dekatron
Join Date: Mar 2008
Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.)
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Re: BT exchange modules from NATO command bunker!
Hi,
I hadn't seen so much comms in one place either, until I visited Hack Green Secret Bunker near Nantwich! Cheer, Pete.
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11th Jan 2015, 1:08 pm | #5 |
Hexode
Join Date: Jul 2007
Location: Edinburgh, UK.
Posts: 344
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Re: BT exchange modules from NATO command bunker!
Hi,
Just to the left of the large test set on the right hand side of the picture you can just see at least two "shelves" of voice frequent telegraph equipment. Among the other equipment there are several shelves of FDM multiplex equipment providing lots of voice circuits. That is certainly a very comprehensive set of communications equipment and related test equipment that they have installed there. From memory (45+ years ago) the "valve" used in the VFT equipment was actually a current limiting barretter in the output circuit to the teleprinter rather than a conventional valve. |
11th Jan 2015, 1:58 pm | #6 |
Pentode
Join Date: Oct 2014
Location: Spalding, Lincolnshire, UK.
Posts: 181
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Re: BT exchange modules from NATO command bunker!
Yes you're correct:
http://www.forum.radios-tv.co.uk/vie...hp?f=15&t=1100 I have seen loads of these units and similar end up in demo scrap and skipped. There was a room full at the now demolished post-war AAOR bunker at Uxbridge that was instead used by the Americans: http://www.airfieldinformationexchan...l=1#post122783 |
11th Jan 2015, 6:11 pm | #7 |
Pentode
Join Date: Jan 2009
Location: Liverpool, Merseyside, UK.
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Re: BT exchange modules from NATO command bunker!
Yes
Those are the 50 baud channels we used to run 12 on a 4khz audio channel. The same people supplied 200 baud channels and the associated filters and amplifiers. They required 20 V main supply and then the telegraph supply which could be +- 80 V or +-6 V. they were quite good at demodulating RTTY back in the day. I may have the manual in the attic but I won't be able to look till the end of January. Ian PS don't use them upside down the output was a mercury wettd relay if I remember correctly |
11th Jan 2015, 6:21 pm | #8 |
Pentode
Join Date: Oct 2014
Location: Spalding, Lincolnshire, UK.
Posts: 181
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Re: BT exchange modules from NATO command bunker!
The manual would certainly be interesting if you find it.
They do indeed contain a mercury-wetted relay. I assume it's OK to store them any way up? I hope so! |
11th Jan 2015, 9:55 pm | #9 |
Hexode
Join Date: Jul 2007
Location: Edinburgh, UK.
Posts: 344
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Re: BT exchange modules from NATO command bunker!
Hi,
Relays with Mercury wetted contacts usually have an arrow symbol printed on them so that they are kept the right way up! |
11th Jan 2015, 9:59 pm | #10 |
Pentode
Join Date: Oct 2014
Location: Spalding, Lincolnshire, UK.
Posts: 181
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Re: BT exchange modules from NATO command bunker!
Hmm, well I assume that will be the same way as the modules are designed to sit in the rack when in use then!
What happens if they are stored incorrectly? |
11th Jan 2015, 10:10 pm | #11 |
Hexode
Join Date: Jul 2007
Location: Edinburgh, UK.
Posts: 344
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Re: BT exchange modules from NATO command bunker!
When the equipment is the right way up the relay is the right way up. After a couple of weeks or so gravity will sort the mercury out and the relay will probably work ok again. The Mercury was there to eliminate problems due to contact bounce.
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11th Jan 2015, 10:19 pm | #12 |
Pentode
Join Date: Oct 2014
Location: Spalding, Lincolnshire, UK.
Posts: 181
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Re: BT exchange modules from NATO command bunker!
I see, that makes sense. Many thanks.
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12th Jan 2015, 8:03 pm | #13 | |
Hexode
Join Date: Jan 2013
Location: Ă…lesund, Norway
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Re: BT exchange modules from NATO command bunker!
Quote:
The method of construction has many similarities and components. Short term memory loss isn't much fun. |
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12th Jan 2015, 8:34 pm | #14 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,951
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Re: BT exchange modules from NATO command bunker!
The valve is indeed a current-controller for the +/-80V TTY loop. There was a later plug-in substitute that had several "CV"-type metal-can TO5, one TO126 plastic transistor and a red LED serving the same function.
'Borrowed' instances of this TO126 transistor [I suspect MJE340 or equivalent] could produce about five Watts of RF on 1.8MHz when fed with a 150-Volt HT supply, as some oldtimers at the New Southgate ARC could no doubt describe. |