Soldering Flightcom 403 DSub connector

Unlike my Icom radio harness connector, which uses a crimped molex pins, my Flightcom 403 appears to require that the wires be connected to the Dsub connector by soldering them. Soldering and (especially) fabricating wire harnesses are new skills I'm learning. Thus...

Are there any keys to doing this or is it just a matter of holding the wire to the appropriate Dsub pin on the connector and soldering away? Other than making sure I have good strain relief by using the clamp provided with the connector, any other things or techniques I should to keep in mind? Regular 60/40 rosin solder OK I assume?

The connector itself looks pretty simple. If I mess it up will it be pretty easy to find a replacement locally at Radio Shack or something?

Thanks for any general suggestions.

Why not use crimp-style Dsub connector? Radio Shack will have it... it's a bit easier than soldering..

I'd vote for the crimp pins also!

I agree with Radomir!
You didn't say if you have done any soldering before so excuse me if I tell you something you already know. You need a pencil soldering iron, rosin core solder a damp sponge, heat shrink tubing, and a steady hand. If you have not soldered before you should try soldering a few wires together to get the "touch" just right. You don't want to end up with a cold solder joint (greyish rough looking) or have too much heat and start melting the insulation back. You need to strip the insulation so it is close to, but not touching, the connector. I put a small piece of heatshrink on each pin that I shrink down with a heat gun after soldering the pin. This helps add some support to the wire where the solder has wicked up under the insulation. Wipe the tip of the iron on the sponge between each termination to keep it clean.
Having told you all this, I would order crimp shells from Digikey or one of the other electronics houses. I don't care for the Radio Shack connectors because they use the stamped pins which can get flackey! (Experience from work!) Here is the url for digikey's CONEC D-subs that I have used. The pins are listed on the upper right side of the page. These pins are solid with gold plating for good reliability. Hope this helps.

http://dkc3.digikey.com/PDF/T081/0258-0284.pdf

Paul
N694BP reserved

Thanks Paul and Radomir.

I'll look into the crimping method. The only disadvantage is that I'll need to buy another tool, new connector, and pins. (The connectors for the harness come provided with the intercom.) It looks like Steinair sells a d-sub crimper for $40.00, so maybe not a big deal.

My brother-in-law is an EE with avionics application experience, so I should have a good tutor if I go the solder route. He already gave me the solder equipment that Paul mentions. If I understand your helpful advice, Paul, do you mean to say that if you have, say, a 25-pin connector, you'll use 25 pieces of small shrinkwrap over each of the soldered connections? Then, I assume, one piece of larger shrink wrap over the entire bundle before clamping it down?

Thanks again.

The soldering is a skill task

Use SN63 flux cored solder rather than SN60 because it has no plastic state in the transition from solid to liquid - thus less chance for a disturbed joint. Mate the connector to be soldered with another connector to help hold pin alignment during the solder process. Configure a stable connector support that holds the connector at an angle with the cutaway portion of the pins facing upward. Strip and tin each lead before attempting to solder it into the pin. Insert the wire into the pin so that the wire is bottomed out and the weight of the hanging wire is pulling the upper stripped portion of the wire against the back of the pin where it is not cutaway - this stabilizes the wire in the joint configuration so that it will not move as the joint cools through the transition temperature. Use the pencil iron as described above contacting both the wire and the pin. When it goes liquid get the iron off of it and let it cool. You want to avoid reheating the joint but sometimes you have to add more solder. Inspect the joint for shiny solder, with concave fillets and feathered edges to the base metals. If you get a joint that does not satisfy these criteria but the solder is shiny (no evidence of a cold or disturbed joint) the joint is strong and not shorted to an adjacent pin, just live with it. Shrink a sleeve on it and move on to the next pin. Do not add a big sleeve to the entire connector.

Got to go to Wal-Mart for groceries. Good luck.

Bob Axsom

Go ahead and solder...

There is nothing wrong with a good solder joint as long as the wires are supported.

The D-Sub back shell should provide this support, and as usual, AeroElectric Bob has some good notes on how to do it....

http://www.aeroelectric.com/articles/dsubs/d_solder.html

Just follow Bob's instructions, no need to rent/buy/borrow/steal a fancy crimper, which will probably not even have the dies recommended by the connector pin manufacturer...

gil A

PS ...Crimping is a skill task too, if done right. Just as anyone who uses them for critical production about the regular calibration procedures (of both the tool and the operator) required.

Thanks Bob for the good description and thanks Gil for the link to Aero Bob's article. Pictures are worth a thousand words for me, so it is very helpful. (And 63/37 is actually what I have. Just mis-typed 60/40).

And, yes, Gil, I am happy to hear that soldering is a good way to go. By this point in the build, I've discovered that the difference between $50K RV's and $80K RV's are just a lot of little decisions like this.

az_gila said:

PS ...Crimping is a skill task too, if done right. Just as anyone who uses them for critical production about the regular calibration procedures (of both the tool and the operator) required.

Click to expand...

I am very much a novice at this but I have found that getting good quality crimps doesn't happen naturally. I have found that the less expensive crimpers produced the least consistent good crimps and the more expensive ones produced consistently better crimps but not always perfect (user error I'm sure). If you mess up a crimp you have to cut the end off which leaves you with one or more shorter wires. If you mess up a solder you can re do it without cutting it off. D sub connectors at Radio Shack are cheap. I bought a few to practice on.