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Old 30th Oct 2019, 9:25 pm   #1
Sean Williams
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Default Unit Telegraph No.55A

Has anyone got any experience of these units - Look to be a V21 modem that converts to 80-0-80.

Information is scarce to say the least, so has anyone actually worked with them during the early to mid 1980s?

Ideally, a full manual, and tech training notes would be really handy, but personal recollections will be just as useful.

Cheers
Sean
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Old 30th Oct 2019, 9:34 pm   #2
mike_newcomb
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Default Re: Unit Telegraph No.55A

Hi Sean,
any chance of some photos please.
Thanks - Mike
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Old 30th Oct 2019, 10:37 pm   #3
Sean Williams
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Default Re: Unit Telegraph No.55A

Hi Mike,

It really iant that interesting inside, but here is a picture anyway
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Old 31st Oct 2019, 11:59 pm   #4
Pellseinydd
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Default Re: Unit Telegraph No.55A

Quote:
Originally Posted by Sean Williams View Post
Has anyone got any experience of these units - Look to be a V21 modem that converts to 80-0-80.

Information is scarce to say the least, so has anyone actually worked with them during the early to mid 1980s?

Ideally, a full manual, and tech training notes would be really handy, but personal recollections will be just as useful.

Cheers
Sean
Just looked in the 'Vocabulary of Engineering Stores' for 1985 and it only lists 'Units Telegraph 52A' which is a 12 volt to 80 + 80 converter. Looks as though it is after that date. After my time on telegraphs

Ian J
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Old 1st Nov 2019, 8:13 am   #5
Sean Williams
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Default Re: Unit Telegraph No.55A

Thanks Ian,

This is interesting - the two machines that I have both date to the early 1980s - I am guessing that there must have been a fundamental change to the Telex network when exchanges were phasing out Strowger?

Perhaps when tone dialling became more usual, and as part of this upgrade, these units were required?

Guessing I might need to take a trip to the BT archives t see if they have anything newer - I would really like to get hold of some technical documents to support these units.
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Old 1st Nov 2019, 1:51 pm   #6
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Default Re: Unit Telegraph No.55A

I only had a limited exposure to Telex with Mercury, but As I understand it the BT Telex network was separate to the telecoms network and when it was being phased out in favour of datacoms such converters would enable older machines to continue in service for the remainder of their service lives. Probably simplified!
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Old 1st Nov 2019, 5:38 pm   #7
mike_newcomb
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Default Re: Unit Telegraph No.55A

Hi Sean, I really wanted a photo of the front, as Number 55A seemed familiar.

This is because from the late 70's through the 80's I was quite involved with Telex and Telegraph, both National and International.

Originally we had free standing Type 15 then 23 (Teleprinter) Machines, which over time were phased out. Replaced by connecting to a Message Switcher, also a mini Computer. One of the projects allowed Telex connection from anywhere in the World to access the Computer and using formatted messages act as a Computer Terminal.
This was before Viewdata and the WWW.

Another Converter I recall was the DCE3 or DCE3A from BT.

Some memories from then:

a) Wiring was different to telephones, being 3 wires plus earth.
We had a intermittent fault that occasionally partially garbled msgs.
It required the expertise of a highly skilled BT Engineer (Tony?) to locate and correct.
He found the 0v and earth on one of the circuits had been swapped.
Thus occasionally earth interference when sending or receiving caused this.
b) BT invested much in bringing upto date the (Telex) Keybridge Exchange and we were promised a Tour when complete,which sadly did not happen.
Problem was Fax's appeared around this time, which used standard Telephone lines and replaced many Telex Circuits.
c) Formatted msgs were required when accessing the Computer.
On UK machines there was a newline key that sent singe carriage return AND Line Feed control charters.
Some Countries (eg Canada) did not have this and addition characters were being sent such that msgs were incorrectly formatted and rejected.
Seem to recall their machines had an option to send 2 Line feeds when manually entered.

Regards - Mike
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Old 1st Nov 2019, 5:56 pm   #8
Sean Williams
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Default Re: Unit Telegraph No.55A

No Problem Mike,

I will take a pic of the unit all in its case.

It just has a brown plastic cover though.

I would think that cou came across the Cheetah 85 and 87 then - These are some of the machines I am currently working on.
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