PDA

View Full Version : Some LMR cable tips.


David L. Vrablic
01-18-2008, 02:43 PM
a. I use a PVC pipe cutter to get a nice clean square cut on LMR 400-600-900.

b. I find it a good start to run a couple of strokes with a 1 inch double cut flat file to make sure the center conductor is flat across the whole cross sectional area of the center conductor. You will see why later.

c. Yes I remember most of the time to slip on the shrinkable tubing, and the crimp ring on the cable before I proceed as it can get messy afterward with DB cable goop once the braid is exposed.

d. I use the nifty "Overpriced" Times recommended prep tool for the first stage cut and remove the outer jacket and most of the poly exposing the proper amount of the center conductor. It removes all but a thin layer.

e. I have a small ceramic knife that seems to be better than a razor knife as it does not nick the copper or deposit dissimilar metals on the copper surface.

f. Once cleaned of all remaining insulation.
I reach in my cable kit and pull out a little palm sized AA battery powered screw driver.(You can always get AA batteries somewhere)
I cut the shank down on the wooden handled chamfer tool that Times recommends and I chucked it in this little guy permanently.
It only takes a couple of seconds to put a neat little nub on the end of the center.
Remember all that attention to a square end to start with? Well it pays off when the end fits perfectly in the chamfer tool and yields a rounded "nub that will slide into the internal collett of the EZ connectors with no problem.

g.Go ahead and flip the jacket removal tool over and make the second stage outer jacket removal cut and flare the braid out from the aluminum jacketed insulation about a 1/4 inch.

h. Another little trick at this step..
Get a hold of a pair of those toe nail cutters that are like the fingernail clippers we all use. It is best if they have a concave blade and are about a half inch wide.
Don't get crazy but snip the harsh aluminum edge about a 1/16th inch all around. It yields a little chamfer that doesn't get hung up when you try to seat the connector in place.
This also eliminates those annoying "Frog Hairs" that sometimes wander awfully close to the center conductor.

I follow the Times video directions for everything else so I won't go into a detailed diatribe on what most everyone knows and does every day.
I just thought you might get a kick out of a couple of bits that work for me.

Oh yes, I know they are expensive but I am developing a fondness to the solder pin N/ angle connectors. Great for the new duplex dish feeds and the PAC slotted waveguide sectors that have the connector right out from the front. At least you know it isn't shorted when you screw the little cover on.

I hope this help someone! If you aren't having any problems FIGITABOUTIT and continue with what you know works.;)

cephlon
09-17-2008, 03:27 PM
Dave,
Thanks for the great tips.
The part I seem to have the most trouble with is the soldering part. I am not a very experienced solderer and I can't seem to get the solder to melt inside the center conductor correctly.
I am following the tips here : http://www.timesmicrowave.com/content/pdf/TC-400-NM.PDF


Any tips?

David L. Vrablic
09-17-2008, 04:34 PM
Dave,
Thanks for the great tips.
The part I seem to have the most trouble with is the soldering part. I am not a very experienced solderer and I can't seem to get the solder to melt inside the center conductor correctly.
I am following the tips here : http://www.timesmicrowave.com/content/pdf/TC-400-NM.PDF


Any tips?

You are welcome glad to help.
Soldering this type of connector is sometimes a bit tricky.
A couple of tip are:
1. The mating surfaces must be free of any contamination, water, oil, tarnish are all bad things.
2. The joint must be physically and chemically clean.
3. Use a good quality rosin core solder.
4. It is good to use a quality rosin flux also.
5. As they recommend in the instruction.
6. Snip a small piece of solder dab it with flux and place it down in the bottom of the connector socket.
7. Applying the heat quickly and evenly is the trick.While you push the pin to the bottom of the connector.
(It helps to have 3 hands and a small block of wood)
It has to flow without melting the insulating media or you can get the connector shell on.
I use a small Weller Jr soldering gun I have had for years.
It is just the right size.
Keep practicing it gets easier over time.;)

DrLove73
09-17-2008, 04:59 PM
I use thin soldering wire of good manufacturer, that can mean a world of difference in heating the solder.

I also layer the solder onto the LMR center wire and then I heated it, then push the center wire inside the pin.

I am sure that some of the techier guys will correct me how to do it properly, but it works for me. I again stress the quality of the soldering wire.

go.fast
09-17-2008, 08:06 PM
You guys soldering the times EZ's?

c.davis
09-17-2008, 08:40 PM
When I soldered connectors, I used the ground wire from typical 14/2 household wiring in my trusty old Weller (replaced the stock irons with the 14g wire). Before I attached the wire into the weller iron I took and wrapped it nice and tight around the connecter end (small copper/brass center piece) to gauge size. From there on I had a nice holder to place the connector end into and heat up enough to melt solder and then put the exposed cable into.. worked like a charm and only required two hands ;-)

The great thing about all of this is that copius amounts of ground wire from 14/2 is easily found for replacement, easy to bend/wrap, conducts very well and, if wrapped twice to get "formed", holds the connecters quite well (freeing the mystical "third" hand).

Note: Each "fresh" piece of ground wire from 14/2 smokes and stinks for a minute while it burns off its initial coating... Expect to use about 14" of 14g wire to make things comfortable and, as David mentioned, get a piece of 2"x4" to press against so you don't go marring other things. Also, the wire will expand upon the first couple of heated uses so some tightening around the connectoer will more than liekly be required.

mrmike
09-17-2008, 09:34 PM
Clean the solder with a clean cotton rag. Use liquid rosin for all pieces to be soldered. Heat the centre pin and add a dab of solder to the inside of the pin. Heat the centre core of the LMR (it should be 1/2 inch longer that needed) and add solder. Trim the centre core, then supply the heat to the end of the core, and add the centre pin to the end. When the solder melts, slid the pin onto the core, and a little twist, then remove heat. Do not move anything for at least 5 seconds; doing so creates a cold solder joint. When finished, you should be able to shine the solder joint with the cloth. If the solder appears dull, it a cold joint. This takes practice (we spent a week in class, learning just the basics of soldering).

David L. Vrablic
09-18-2008, 02:53 AM
You guys soldering the times EZ's?

No you silly wabbit?
That is what makes em EZ....No solder.
Thats a joke son!:)
------------
I wasn't fool enough to bring up the new technology because someone would slap me up the side of the head with "I always solder my connectors and I never have any troubles", "besides I can tow a tractor out of a ditch with my cables and they don't come off."
---------
My great Grandma used to use a button hook to fasten up her shoes and she never had any problems either.
Times and products do change over time.

I have switched over to the EZ solderless connectors and (To date after installing hundreds ) I have never had any problems with them.
They do cost more money but my time offsets that.

Use what you can afford and are comfortable using.
---------
Good point about the solder now that ROHS is in place.
I still have some old school 60/40 tin lead solder for special projects.
I know that works. The new solder can be very problematic especially if you don't use it with the correct paste (flux)
That is one of my reason for switching rather than fighting with it.

I really miss the lead fumes! It never "efetcted me none!":o

-------
PS: Great info MrMike you are a very wise man of experience. He knows of what he speaks.
Carl that is a great enough idea that I will steal it. I just don't have any scruples when it comes to "hints and kinks.".

Stratolinks
09-18-2008, 12:11 PM
"My god man drilling holes in his head isn't the answer, the artery must be repaired. Now put away your butcher knives and let me save this patient before it's too late!" - Dr. Leonard McCoy

You did know that Boeing hasn't soldered a connector in more than 30 years, right? The key thing is the proper tool for the job.

When crimping ends on LMR400, you also have to have the appropriate sized die on the crimp tool for the pins you are using. In my collection I now have 3 different dies for LMR400 ends. The outside crimp ring is the same diameter on all the dies, but the one for the pin is different. If you over or under crimp the pin the connector can fail. Most manufacturers of connectors will indicate the crimp diameter for their connectors.

The safest way is to buy the same brand of crimper as you buy connectors.

mrmike
09-18-2008, 10:09 PM
Or, try soldering with an oxy-acetylene torch (seen it)

Stratolinks
09-19-2008, 01:33 PM
Yep, Iv'e done that before in a pinch. It is all about playing with the tank valves to get a small enough flow of gases to keep the flame size down. Also used propane torch many times. I still have a 500Watt electric soldering iron. The tip is chisel shaped about 1" across, most commonly used for soldering joints in eavestrough. (When was the last time anybody did that?) It is a little clumsy for printed circuit board work though!

One place where we installed wireless service was an old stone house, it still has the original copper eavestroughs that were soldered together more than 150 years ago. It has a copper roof too, all the main beams are Oak and the floor joists are all hard maple. They just don't built them like that anymore.


Or, try soldering with an oxy-acetylene torch (seen it)