Coax Connector Failure

[Dockhead]

Originally Posted by goboatingnow

I suspect Dockhead you got some stray braid shorting to the core. It's easily done

Dave

I thought that too, but I tested both cables with a multimeter today, and discovered that there is no short to the core in either case. Which is bad in the case of my masthead antenna, because it is a dipole and is supposed to read shorted. But in any case, it means no stray strands of braid shorted to the inner conductor.

I also tested the braid connection by testing resistance between a multimeter probe stuck into the insulation of the cable further down, and the outer body of the connector. Both tested fine. And actually, how could you screw that up with the Amphenol connectors -- you have screwed the body down onto the braid, which ought to be plenty of contact even if you bungle the soldering part.

I also tested resistance between the inner conductor and the tip of the Amphenol connector -- in both cases, none.

Is it possible that I screwed up both connections on the mast, but got both right below? It seems bizarre to me

[Dockhead]

Originally Posted by Wotname

Even better , try to avoid the PL-259 if at possible. I realize it is not so easy but I try to source antennas with N type connectors and then use crimp type N's.

My masthead connections are Type N. I am more suspicious of my luck with these. They were both crimp types, and I only had a crimper for the smaller one (plus the tips). So I soldered the braid to the larger one. I can well imagine how I screwed that up. That's going to be fun trying to rectify that in a bosun's chair 75 feet above the water.

But not the PL259 on the spreader antenna! I just can't imagine how I screwed that up. The good news is that one is easier to reach. I will go up there on Tuesday when I'm back in Cowes, and try again.

[rwidman]

Originally Posted by Dockhead

I also tested the braid connection by testing resistance between a multimeter probe stuck into the insulation of the cable further down, and the outer body of the connector.........

If you pierced the insulation to test the cable, you might as well take it down, make a new one on the bench and then install the new one. You've ruined the cable you pierced.

[Dockhead]

Originally Posted by rwidman

If you pierced the insulation to test the cable, you might as well take it down, make a new one on the bench and then install the new one. You've ruined the cable you pierced.

That was at the nav table end.

Can't just "take it down" -- it's 90 feet long!

[Paul Elliott]

Originally Posted by rwidman

If you pierced the insulation to test the cable, you might as well take it down, make a new one on the bench and then install the new one. You've ruined the cable you pierced.

Aren't you being a bit harsh? As long as he hasn't pushed the shield braid wires through the center conductor insulation, I see no reason that he can't just seal the hole with liquid tape or something similar. I've even cut and spliced coax before, and while it isn't recommended, it can be done so there is a minimal impedance bump. I wouldn't let a tech install spliced coax on my boat, but if I do it myself in a pinch I can live with it.

[s/v Jedi]

I always measure against my dummy load so that I should see the 50 Ohm from the dummy load plus the cable resistance. Next is a short instead of the dummy load which must show just the cable resistance.

I would buy crimp connectors for all, the tools for each size crimp, and replace the lot. If they have no N-type crimps for the cable you used, I would switch to PL259 crimp instead. You're just not going to do the soldering of the screen in a bosun's chair. Not even on deck I think (the slightest breeze cools it down too quick or even prevents you to reach soldering temperature).

Also, your RG213 might be good but the small RG58 stub into the antenna might have the problem. Check that too.

What kind of mount did you get for the HAM antenna? I only use NMO but even that needs to be tested well when the antenna is screwed onto it.

[Wotname]

Originally Posted by Paul Elliott

Aren't you being a bit harsh? As long as he hasn't pushed the shield braid wires through the center conductor insulation, I see no reason that he can't just seal the hole with liquid tape or something similar. I've even cut and spliced coax before, and while it isn't recommended, it can be done so there is a minimal impedance bump. I wouldn't let a tech install spliced coax on my boat, but if I do it myself in a pinch I can live with it.

+1
At the end of the day, we are only talking 150MHz not say 4 GHz.
Everything on a cruising boat ends up as some compromise!

[St. Elsewhere]

Dockhead,

I did not read what you were using for heat in soldering the PL259's. I had trouble when using a soldering gun, but switched to a fine point torch and have had no trouble since. The problem is that the braid part of it requires more heat. It takes a little practice to get good flow without too much heat, but when you get it to flow and remove the heat quickly it works.

[Dockhead]

Originally Posted by St. Elsewhere

Dockhead,

I did not read what you were using for heat in soldering the PL259's. I had trouble when using a soldering gun, but switched to a fine point torch and have had no trouble since. The problem is that the braid part of it requires more heat. It takes a little practice to get good flow without too much heat, but when you get it to flow and remove the heat quickly it works.

A Weller soldering iron, which I bought specially for the purpose after reading up on how to solder on these connections. It seemed to go well, and looked like the photos look in the instructions.

Besides that, is there really much likelihood of failure soldering the screen into the Amphenol PL259? After all, the silver-plated body of the connector screws down onto the screen. Looks to me like the solder is belt and braces (and it looks to me like and elegant, relatively idiot-proof design), where the screen is concerned. Soldering the tip is a cinch, and clearly visible whether you succeeded or not. Maybe I don't understand something? If you cut and trim the cable correctly, it doesn't seem like rocket science to me. Therein perhaps my problem

[Dockhead]

Originally Posted by s/v Jedi

I always measure against my dummy load so that I should see the 50 Ohm from the dummy load plus the cable resistance. Next is a short instead of the dummy load which must show just the cable resistance.

I would buy crimp connectors for all, the tools for each size crimp, and replace the lot. If they have no N-type crimps for the cable you used, I would switch to PL259 crimp instead. You're just not going to do the soldering of the screen in a bosun's chair. Not even on deck I think (the slightest breeze cools it down too quick or even prevents you to reach soldering temperature).

Also, your RG213 might be good but the small RG58 stub into the antenna might have the problem. Check that too.

What kind of mount did you get for the HAM antenna? I only use NMO but even that needs to be tested well when the antenna is screwed onto it.

This sounds sensible, and I guess that's what I'll do. Wow, that's going to be fun, 75 feet above the water. I'll have to think through very carefully how I'm going to test everything from up there. Maybe makes sense to have someone below ready to test while I'm still up there.

As to the ham antenna, on the recommendation of a very knowledgeable guy at one of the online ham radio equipment suppliers in the UK, I bought a long (1.2 meter) Diamond antenna with its own radials. He didn't think the spreaders would provide a good enough ground plane, and I agreed -- my antennae are mounted on stainless steel plates carefully isolated from the spreaders in order to prevent galvanic corrosion.

It's a pole mount, like my other spreader-mounted antennae, so it is clamped to a stainless stub of a pole welded to stainless plates riveted to my spreader. It is extremely sturdy.

It is tuned for the 2 meter and 440 cm ham bands. The 2 meter ham band is a little lower frequency than marine VHF, but I figured that if you were getting good results on marine VHF with your antenna, then this should be ok too.

[goboatingnow]

You can see Dockhead why the Russians never achieved much with those spy trawlers !!!


Keep on rocking, be safe

Dave

[St. Elsewhere]

Originally Posted by Dockhead

Besides that, is there really much likelihood of failure soldering the screen into the Amphenol PL259?

If you Google "cold solder joint" you will find a great deal of information that suggests that not only is there a possibility of an initial problem, but a risk of future problems resulting from cold solder joint corrosion. The issue of corrosion is a concern with crimp devices as well, especially in areas exposed to weather and salt air.

I am not an expert, but I think that research of this issue would cause me to do properly soldered connections installed the next time the mast is down. I know others have posted reports of trouble free crimp devices, but corrosion is a worry in such a metal joint.

[rwidman]

Originally Posted by Paul Elliott

Aren't you being a bit harsh?.............

Not in my opinion and I am an experienced electronics technician. Only a hack would pierce insulated wire for testing. If his (or your) standards are lower than mine, fine, but he has now created another potential point of failure.

[Lake-Effect]

A boatload of good advice in this thread.

I've seen the PL259's soldered maybe 10 different ways, with at least 8 of those wrong. This is possibly the trickiest soldering task in boating, especially on a chilly windy day. I've seen people botch the twist-on type as well.

Dockhead - if you could borrow a VHF SWR meter and a 50-ohm load, one trip up the bosuns chair with the load while a friend operates your radio and checks the readings will confirm whether you need to remake any connections.

(Be sure to test your radio with the SWR meter and load and a short piece of antenna cable first, so you know it's OK)

I wouldn't deliberately pierce the jacket of a cable where it's exposed to the elements, but a light pierce just to the braid, inside the boat, shouldn't really be a problem. Covered with adhesive heatshrink, or even a few wraps of electrical tape, I wouldn't expect the cable to fail prematurely at that point.

[HappyMdRSailor]

Originally Posted by Lake-Effect

A boatload of good advice in this thread.

I've seen the PL259's soldered maybe 10 different ways, with at least 8 of those wrong. This is possibly the trickiest soldering task in boating, especially on a chilly windy day. I've seen people botch the twist-on type as well.

Dockhead - if you could borrow a VHF SWR meter and a 50-ohm load, one trip up the bosuns chair with the load while a friend operates your radio and checks the readings will confirm whether you need to remake any connections.

(Be sure to test your radio with the SWR meter and load and a short piece of antenna cable first, so you know it's OK)

TONS of fantastic advice from highly knowledgeable here.... BUT... I like this on the BEST so far!!!