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#45489 - 11/30/04 06:30 PM Grounding Mil-Spec cable  
rad74ss  Offline
Member
Joined: Apr 2004
Posts: 156
Pryor, OK USA
I have to add ground wires to Mil-Spec cable that has a braided shield. I have been looking all over the net for either the ferrule type hookups or the solder tube type. I can only find one place that has the solder ones and they are a bit expensive.

Does anyone out there have any experience with these types of devices or know where I can find a supplier?


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#45490 - 12/02/04 01:20 AM Re: Grounding Mil-Spec cable  
mhulbert  Offline
Member
Joined: Oct 2004
Posts: 132
Anaheim, CA USA
What are you terminating to? I would take a crimp connecor and after twisting and trimming, crimp the braid under it. If it's critical, use the connectors with the copper/brass inserts, they would give you a better connection. Shrink wrap if needed.

Don't solder! It will wick up the braid which then make it brittle, and it WILL break off over time. I have troubleshooted a ton of audio lines where this happened under med to hard abuse. It's impossible to keep the solder from wicking up, so crimp is the way to go!


#45491 - 12/02/04 04:35 AM Re: Grounding Mil-Spec cable  
SimonUK  Offline
Member
Joined: Oct 2004
Posts: 50
Ayrshire, Scotland, UK.
What kind of mil spec cable are you using. I've just finished working for the UK military after nearly 20 years and spent most my time on wiring harnesses, ATE's and torpedos.

After stripping back insulation and braid a ground was attached to the braid using a solder sleeve.

The main problem was strain relief (lack of) in the harnesses which led to failure of not just the grounds but the other conductors as well. Also the solder sleeves would cut into the insulation of the conductors resulting in some very spectacular test failures and incredible rework times. Most cables were well strained between the plugs or sockets cable clamps and the terminal pins.

The most annoying terminations were into Lemo co-axial and tri-axial connectors, especially the FFA.OS series. You had to trim the insulation 10 mil from the end of the cable and leave 4 mil of braid for the gland and then bare the conductors 2-3 mil and solder to mil standard 2000, !*@$£".

Most of the cable we used was manufactured by Raychem and is a right pig to work with.

The connectors used were Hypertac, Raychem, Lemo,ITT-Cannon, Socapex, Thomson-CSF amongst others.

Some of the hypertacs had 150 pins!!!

Hope this helps.

Simon.


#45492 - 12/02/04 10:21 AM Re: Grounding Mil-Spec cable  
rad74ss  Offline
Member
Joined: Apr 2004
Posts: 156
Pryor, OK USA
M27500-20TE3T14 M27500-20TE2T14 from Wiremasters. They sent me a cut sheet on the solder tubes they carry yesterday. However cost is the big issue. This isn't a critical system and isn't in a high vibration environment. It is an air conditioner for a fixed radar. The control panel is indoors, as well as the compressor/evaporator/blower stack. The condenser is outdoors and is electro-polished.

We are using Cannon plugs and half of them only use 9 to 12 pins. We have a government reg. for how to solder the ground wire to the braid, then shrink seal the ground to the cable. It works well and provides extra braid length behind the soldered area for flexibility, but it looks like crap. It is also difficult to get the workers to do clean solders. I only have one I trust to do a perfect job every time. I am going to try to get her a bonus check for her good work and excellent attitude. There were only two minor mistakes on a panel with over 2500 individual points.

The tubes from wiremasters are the shrink tubes with seals at either end and the solder ring in the middle. The cable insulation is Tezfel.

I still do not think that the government and my company wants to make these any more expensive as they probably won't be looked at except for maintenance. I am just a stickler for aesthetics.

I used to work on these plugs when I was a Submariner and I feel your pain on the massive 100+ pin cables, especially when you can only get to them by crawling between the back of the equipment and a bulkhead!


#45493 - 12/02/04 02:58 PM Re: Grounding Mil-Spec cable  
rad74ss  Offline
Member
Joined: Apr 2004
Posts: 156
Pryor, OK USA
Wiremasters Inc. has them for .50 each in bags of 100. www.wiremasters.net

Tyco or one of its subsidiaries has them as well, but I couldn't get a price.



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