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Test Equipment Anonymous (TEA) group therapy thread

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mnementh:
Yeah... yo momma come back just to    if you buy dat...  :-DD

mnem
 :-/O

mnementh:

--- Quote from: tggzzz on June 27, 2022, 02:08:00 pm ---
--- Quote from: Cerebus on June 27, 2022, 12:30:50 pm ---
--- Quote from: tggzzz on June 27, 2022, 09:52:25 am ---... 2400nm was unarmoured, 300nm armoured. ...

--- End quote ---

I don't think 2.4 micrometres of armour is going to make much difference.  >:D

--- End quote ---

Sigh. The other nm in common use all around the world, i.e. not just USA.

But you knew that :)
--- End quote ---

So newton-metres then...? >:D

mnem
:popcorn:

tggzzz:

--- Quote from: bsdphk on June 27, 2022, 12:44:49 pm ---
--- Quote from: tggzzz on June 27, 2022, 09:52:25 am ---
--- Quote from: bsdphk on June 27, 2022, 08:20:03 am ---I doubt that cable is for sub-sea use, almost all such cables have at least one layer of steel, and much thicker envelopes.

--- End quote ---

No, they don't. A major design constraint is the need to fit as much as possible cable on a cable-laying ship, and that precludes steel armour.
[…]

The TAT-7 cable was steel core, […]

--- End quote ---

I didn't say "steel armour", I said "layer of steel", because you are quite right that at depth that is usually a steel "strength member" at the center of the cable.

--- End quote ---

I wouldn't call a central solid steel core a "layer".


--- Quote ---The steel, or on a few very early cables: bronze, is necessary to prevent the length of cable hanging from the laying ship to the bottom of the sea from being stretched or pulled apart.

--- End quote ---

Yup.


--- Quote ---Air-dielectric coax-cables, like the one on the picture, has the additional weakness of a very fragile cross-section, which is why they were almost never used for sub-sea applications.

--- End quote ---

When I quickly looked at it last night it appeared that the core was solid, but broken with age and mishandling.

Looking at it now under good light, it does appear to be air cored with some plastic spacers at unknown intervals. The plastic isn't resilient any more.


--- Quote ---Summa summarum: The cable on the picture has no strength-member, steel or otherwise, and the very thin jacket offers insufficient mechanical protection against compression of the coaxial members, so that is clearly not a cable for sub-sea use.

In fact, I'm not even sure it is a cable for direct burial, it might be designed for use only in conduit.

I'd be curious to know what conduit. I'm also curious to know why there are also PCQ wires.


--- End quote ---

The air core might well be a problem with subsea pressures.


--- Quote ---PS: If you want to to read about the challenges of running coax under the Atlantic, the Bell Systems Technical Journal has excellent articles from the entire history of that practice.

--- End quote ---

I have Arthur C Clarke's "Voice Across The Sea" and "How The World Was One", which contain useful information.

I used to know the chap at GPO Martlesham Heath who designed grappling mechanisms used to retrieve deep ocean cables so they could be repaired on the cable-laying ships. Given the cost of running those ships, you want to be very sure that the grapple works first time!

tggzzz:

--- Quote from: mnementh on June 27, 2022, 02:21:54 pm ---
--- Quote from: tggzzz on June 27, 2022, 02:08:00 pm ---
--- Quote from: Cerebus on June 27, 2022, 12:30:50 pm ---
--- Quote from: tggzzz on June 27, 2022, 09:52:25 am ---... 2400nm was unarmoured, 300nm armoured. ...

--- End quote ---

I don't think 2.4 micrometres of armour is going to make much difference.  >:D

--- End quote ---

Sigh. The other nm in common use all around the world, i.e. not just USA.

But you knew that :)
--- End quote ---

So newton-metres then...? >:D

mnem
 :popcorn:

--- End quote ---

Got it in two.

mnementh:
I knew the incredibly obvious answer would torque you off a bit.  >:D

mnem
But in my heart, I was longing for nebulium. :P

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