Coax Connector Failure

[Dockhead]

Originally Posted by Quirocat

Just installed my new vhf radio, went up the 16m mast, fot the first time-yikes, removed the old antenna, installed the new one with coax connector(please work,), spliced the new cable to the huuuge old one at the masthead and had wifey puuuullll. Nada. Back down the mast with my burly arms and puuulled, nada. Back up the mast with a string spliced to the old cable at the base, and pulll. Nada de nada. Any suggestions as to how to get the old cable out so i can finish the install?

I can't imagine doing that with the mast up. It was hard enough for me with the mast down. Even if your large cable is not cable tied, there may be spots you might have to work it out of. Is it defective? I would leave it until the mast is down next, if I were you, unless it simply doesn't work.

[S/V Pearl]

Dockhead, when I got my extra ticket I bought myself a MFJ259B antenna analyzer for a present. Nice piece of gear - supplies it's own power so you can test antenna without radio. First time I used it and was getting 3:1 swr - had to a bad meter or antenna, I had soldered on the PL259's. Took antenna down (Shakespeare 131-170MHz - great for marine and ham) wiggled the connector and the SWR jump around and would even get down to 1:1.1. I crimped on a new connector and haven't soldered one since.

I have a customer that had a bad radio, tested the antenna for him and it was fine - my fear was that he would buy a new radio, transmit into a bad SWR and if the antenna was bad fry the new radio. Example of versatility of meter - people on the dock will love you (or hate you if you find something).

Nick is right about having a dummy load around. I like the ones available on Ebay that came out of commercial installations, look like a heat sink with a N connector - bought a celwave for a friend good to 250W, about $30 if I recall. I have a small one up to 50W that I used for VHF on boats.

Also have a Diamond SX200 power and SWR meter in the shack - I like this one as it will do 2M and marine VHF in addition to HF, <$100.

Good luck and let us know where the error lies.

Keith, N4KDJ

[rwidman]

Originally Posted by nigel1

Just been through the same process, and discovered that the helpful boat builders had cable tied the antenna cable to all the other cables going up the mast...

Sometimes you will find that. It can be easier to pull one bundle than several individual wires. You solutions are either to pull all the wires out and pull them back with your new wire in place or try to pull the new wire separately. An electrician's snake can be your friend here.

[rwidman]

Originally Posted by Quirocat

Just installed my new vhf radio, went up the 16m mast, fot the first time-yikes, removed the old antenna, installed the new one with coax connector(please work,), spliced the new cable to the huuuge old one at the masthead and had wifey puuuullll. Nada. Back down the mast with my burly arms and puuulled, nada. Back up the mast with a string spliced to the old cable at the base, and pulll. Nada de nada. Any suggestions as to how to get the old cable out so i can finish the install?

Sometimes a wire will pull in one direction but not the other. Try pulling it the other way and see if it works. Sometimes it will not pull at all because it's bundled to other wires or otherwise fastened in place. Try running the new one as in my post above.

[hellosailor]

Dockhead, the hard part of soldering a 2x9 comes from needing enough heat to get the connector body and the braid both hot enough to melt and flow solder--while keeping the braid cold enough not to melt the inner insulation. And keeping that situation long enough to flow solder through those little holes into the braid.

I've found that it is simpler to use solder paste (Solder-It) on the braid before inserting it into the fitting. Instead of trying to flow solder in through the holes, now all you are trying to do it get enough heat on the fitting, and when you can see the white flux flowing in them, you know you've also heated the paste enough to melt it and can stop quickly to cool it down.

The stuff is pricey, and it turns solid in the tube in a year or two so it has a limited shelf life. And of course it isn't necessary--but it makes the soldering very easy.

Your 2m antenna on the spreader may show SWR problems even when the cabling is fine, if the rigging or mast is reflecting enough energy back into it. But it is also possible these days, with antennas having internal loading coils, etc., to simply get a bad one DOA in the box.

[skipmac]

Had an unrelated question about antennas and called Shakespeare and since I had tech support on the line thought I would ask them about connectors.

Not sure if this is the official position at Shakespeare but the tech I spoke with said soldering the braid inside the PL259 through the holes in the side is almost guaranteed to overheat the insulation around the core and he recommended pulling the braid through the holes and soldering the braid to the outside of the barrel of the connector.

Any comments about this idea?

[hellosailor]

Nice idea, skip. From their point of view--and most boaters--they'd rather sell a couple of ten buck proprietary crimp connectors and not get the support call, than try to explain to folks they need to buy maybe four or five extra 2x9 connectors and practice soldering till they get it right. And, maybe a new soldering gun as well.

Many ways to skin a cat, whatever works for you.

Guaranteed to overheat? Sure, until you get some practice.

[skipmac]

Originally Posted by hellosailor

Nice idea, skip. From their point of view--and most boaters--they'd rather sell a couple of ten buck proprietary crimp connectors and not get the support call, than try to explain to folks they need to buy maybe four or five extra 2x9 connectors and practice soldering till they get it right. And, maybe a new soldering gun as well.

Many ways to skin a cat, whatever works for you.

Guaranteed to overheat? Sure, until you get some practice.

Think you've got it right. Recommend the idiot proof solution to keep the idiots from repeatedly calling tech support.

I'm interested in the solder paste solution. I have never used that stuff and always kind of ignored it when I saw it on the shelf. I guess I thought it was some kind of flux or something but guess it is solder in a paste form. (NOTE: looked on the internet and see paste flux and paste solder so maybe there are two kinds of paste?)

So the paste technique is to coat the braid (thickly, thinly, fill the cavity or ?), insert braid into the PL259, heat until the paste melts and you're done? Would it be advisable to hold (not by hand of course ) the connector vertical with the pin up so any extra solder would run down instead of possibly into the pin and create a short or is that not a concern if just the right amount is used?

Would paste give equal/better/worse connection and long term reliability than standard electronics solder? If using solder and not paste what about using a low temp solder instead of standard 60/40? I see some special grades that include bismuth or indium for lower melting.

I do have a Weller gun and maybe should set up the tip like the photos in a previous post or just buy a new Weller iron with a big tip and notch it also like the photos. I do have a couple of spare PL259s and maybe the solution is to melt a little solder and see what I get.

[rwidman]

When I was working, there was a "TV crew" who installed and maintained cable TV systems inside school buildings. All the connections used PL-259 connectors. Those guys soldered them on a routine basis without melting insulation, etc. They used regular electronics solder and the big Weller (I believe 240 watt or so) soldering guns. A smaller gun or a typical pencil iron will not generate enough heat to solder these connectors properly.

[hellosailor]

skip-
Paste flux is "just" flux, typically for pipe soldering, etc. Solder paste is a mixture of flux and solder, usually. At least the Solder-It stuff is. Last time I checked, they made the stuff at Radio Shack (often stale) and sold at Lowes but not HD.

Anything that will melt at lower temperatures is probably a good idea for coax, usually it is slightly more expensive, make sure it is non-corrosive for electrical work and not intended for jewelry, etc.

I've used just enough to wet out the braid, no need to get excessive with it, and then push the cable into the fitting. Little if any paste should push out. I don't put paste on the end of the braid, so I don't worry about it shorting to the center pin. The braid will pretty much soak it up before it can spread that far.

I think soldering guns are one of the few things that haven't skyrocketed in price in the last 40 years, oddly enough.<G> OTOH solder certainly has.

Cheap PL259s, mail order, are easy enough to practice on, with an extra foot or two of cable to cut & toss as need be.

[skipmac]

Originally Posted by hellosailor

Cheap PL259s, mail order, are easy enough to practice on, with an extra foot or two of cable to cut & toss as need be.

Well I think I have a plan. I've got my new cable sitting in the closet waiting for mast rigging time. Think I will get a box full of PL259s and my soldering gear and start putting connectors on one end of the cable. Don't like it, cut off a few inches and put on another until I'm happy with the results. Hopefully it doesn't take more than a foot or three.

[hellosailor]

Skip, if you want a real luxury, there are inexpensive coax cutting tools as well, that will cut the outer insulation, braid, inner, all to the correct length at the same time. Looks a bit like a cigar cutting guillotine, with multiple blades. Not necessary, but awfully convenient. You buy a tool to match your cable size/type.

[Lake-Effect]

Originally Posted by rwidman

When I was working, there was a "TV crew" who installed and maintained cable TV systems inside school buildings. All the connections used PL-259 connectors. Those guys soldered them on a routine basis without melting insulation, etc. They used regular electronics solder and the big Weller (I believe 240 watt or so) soldering guns. A smaller gun or a typical pencil iron will not generate enough heat to solder these connectors properly.

I've sometimes done the method skipjack refers to - making two little 'pigtails' of braid, then finishing those through the shield holes in the PL plug and soldering those to the barrel. The advantage is that you know that you've 100% soldered to the braid because you can see it. Disadvantages: greater chance of a bit of shield bending/breaking and becoming a short, and it's a PITA to pick out the pigtails with a jewelers screwdriver.

I recently watched a marine electrician friend who's installed 100s of these things show me his way. He uses the 240W gun. First he preps the cable in the usual way, with the braid a bit shorter than the inner insulator. He twists the connector onto the outer insulator, solders the center conductor into the tip. Then, starting with one of the braid holes, he heats the connector barrel right there and feeds in solder until the hole is filled. he repeats for the other three holes. It's his belief that even though on the the first or second holes he may not have heated the braid enough to melt solder, by the third and fourth, the connector has become hot enough that solder has flowed a bit inside and has made proper connection to the braid.

I believe he's developed enough of the 'touch' to know when the connectors hot enough to have also heated the braid. It certainly looks clean and the solder's well-melted. He doesn't seem to get callbacks to redo'em...

[rwidman]

Low temperature electronics grade rosin core solder would be your friend here. Electronics grade paste flux can be added to make the soldering process easier.

The connector is large enough that it acts like it's own heat sink, that's why a large gun or iron is needed.

An important point is to melt a small ball of solder on the tip of the iron to help transfer the heat to the object being soldered.

Soldering is an art. There are videos on the Internet that will demonstrate how to solder properly. Anyone who hasn't done this for a living should consider watching the videos and practicing before attempting to do this on their boat's VHF antenna system.

[skipmac]

Originally Posted by hellosailor

Skip, if you want a real luxury, there are inexpensive coax cutting tools as well, that will cut the outer insulation, braid, inner, all to the correct length at the same time. Looks a bit like a cigar cutting guillotine, with multiple blades. Not necessary, but awfully convenient. You buy a tool to match your cable size/type.

One more really useful tool that I will use a couple of times every few years. I'm trying to pare down a little, get down to the essentials. Quite throwing temptation in my face. If I add too many more tools I'm going to have to build a little shed on the aft deck.