This is a tale about how starting down one path can often lead you in new and unexpected directions. Being a boat tale, it of course involves a bit of anxiety, some determination, and the liberal application of dollars to finesse a solution (and purchase some new tools!).
After several weeks of start and stop progress, I was finally in the last stages of installing our AIS system (don’t worry, there will be a blog post on that soon). One of the final steps involved pulling the VHF radio to disconnect the antenna cable and reroute it to the new AIS antenna splitter so that both the AIS and VHF could share the same antenna. That’s when I noticed this:
That’s your typical VHF cable connector, what’s known in the radio world as a PL-259. I couldn’t help but notice that the black cable jacket had pulled out of the body of the connector, exposing some of the cable shield. Hmmm. Better take a closer look. Unscrewing the body of the connector, I discovered this:
This particular model of PL-259 (there are several) requires that you solder the outer connector shell to the shield braid. There are four holes where solder should be applied. But only one had solder in it. The other three were empty. Does it matter? The cable was passing a signal, because we could send and receive on the VHF, but there was a bit more static than I liked. Besides, it wasn’t right, which means it bugged me. So now I wondered “hmmm, I wonder what my other connectors look like.” There are two more at the mast base, where you can split the cable if it’s necessary to take the mast down. The first one was also only soldered in one spot:
Now maybe this is accepted practice in the radio world, I can’t really say for sure. Maybe some of my Ham radio friends can set me straight on this. But I can’t help think that there are four holes there for a reason, and that reason probably isn’t to let you pick your favorite one to use and ignore the rest. Regardless, when I checked the next connector, I knew it wasn’t right:
While it was indeed soldered at each of the (slightly differently shaped) holes, I could clearly see that they were all cold solder joints.
The solder had stuck to the wire shield, but it hadn’t been heated enough to actually flow into the braided shield. This means it wasn’t the best electrical connection.
So why does any of this matter? I mean, the radio was working, right? Well, it all basically comes down to range. If you’re getting signal loss in your cable due to crappy, high resistance connections, then not as much radio energy is making it to the antenna, which means you can’t transmit as far. It might not make a difference when you only sail in bays, but since we intend to be heading offshore in the future, well, I wanted to know we could reach out and touch people from the greatest distance possible.
Now that i knew these connectors weren’t right, I wouldn’t stop worrying about them until I did something. That usually starts with research. I found what I needed at my go-to site for boat projects, Compass Marine.
One of the things I learned is that soldering your cable connectors can cause a problem. The inside of the cable, the part that insulates the center conductor, is made of a plastic material, and too much heat can melt it. Soldering it correctly, where you melt the solder enough to flow into the braid, but not overheat the plastic insulator, is a bit of an art. I elected instead to use crimped on connectors. No heat means no melted insulator and fewer opportunities to screw something up.
Now Hunter Marine used RG-213 coaxial cable when they built Eagle Too. That’s good, because it’s a nice heavy duty grade of cable (e.g. low signal loss over a long run). But it’s larger than what your typical marine electronics shop stocks, which means I had to go to the internet to find the tools I needed.
The crimping tool (top center) and cable stripper (bottom left) I found on Amazon as a set for $43. The critical dimension for the crimper is .429. If you ever need one, just ensure it has a .429 die and says it works for RG-213 cable (your size may vary).
The stripper makes short work of preparing the cable. You just clamp it on the end of the cable and spin it around a few times, and three inset blades make the precise cuts necessary so that you end up with this:
You can do it yourself with a sharp knife and some patience, but the tool literally makes a 30 second job of it. If the blades are a little off and cut a bit too deeply or not quite deep enough, there are adjustment screws on the bottom (and an included allen wrench that stores in the handle) to precisely set the blades for your cable.
The PL-259 crimp fittings I found for $2.30 each on eBay. They’re good quality, with silver plated surfaces and a teflon insulator. I bought 10 in order to have a few to practice with. The cable cutter (lower right in the tool picture) was actually something I was able to pick up at Home Depot for about 12 bucks. You definitely want to use a cable cutter when cutting coax, and not wire cutters, as the wire cutters will crush and deform the cable.
Once the cable end is prepped, you slide on a length of shrink tubing, then the compression sleeve, and then push the fitting onto the end, making sure that the braided shield slides up over the collar on the fitting.
Then you slide the compression sleeve up over the braid and fitting collar:
Slide the shrink tubing over the crimped area and hit it with a heat gun, and you’re almost done (this is a picture of my finished practice piece).
The last step is to hit the center pin with a soldering iron to solder the center conductor to the pin. Yes, I said there’d be no soldering, but this step is easy to do without melting anything:
And that’s about it. The first one probably took me an hour to do. The second one took ten minutes. By the time I did the two at the mast, I was probably down to three to five minutes each:
Did it make a difference? I think so. Maybe it was just a little projection on my part, but after I was done, an automated radio check on channel 27 (you’re not one of those people constantly requesting radio checks on channel 16, are you?) seemed to return a clearer signal. If nothing else, I feel a lot better about the long term durability of these connections. Plus it’s one more hat I can hang in my hat locker.
There’s only one problem now. There’s still one more fitting that needs to be done. The one at the antenna itself. Which is exactly 65 feet above my head. Do I hear any volunteers?