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Author Topic:   Connecting ridiculously small wires
David Pendleton posted 08-10-2009 03:51 PM ET (US)   Profile for David Pendleton   Send Email to David Pendleton  
The NMEA input wires for my Ray 55 are ridiculously small--26AWG or maybe even smaller, I don't have a guage.

Last year, I "permanently" connected my radio to my GPS and when the season was over and I had to remove the radio, I cut the wires.

Well, if I keep doing this the wiring from the radio (it's captive) will eventually be exhausted.

I've looked at Posi-Lock connectors online and they look promising.

Does anyone have any recommendations for a semi-permanent method of connecting these wires? I'd like something a little more elegant than twisting them together and applying electrical tape...

Thanks all.

bluewaterpirate posted 08-10-2009 04:21 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
http://cdn-2-service.phanfare.com/images/ 4892322_2160270_31027066_WebSmall_3/ Image-4892322-31027066-2-WebSmall_0_73804ea65b7559ffc0edab2d27a02d9f_1

Tom

David Pendleton posted 08-10-2009 05:21 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Hey, thanks! I actually have one of those laying around but it never dawned on me to use it.

Forest and trees, I guess.

jimh posted 08-10-2009 08:12 PM ET (US)     Profile for jimh  Send Email to jimh     
There is a problem with many VHF Marine Band radios whose interconnecting leads are not attached to any sort of connector and are just bare wires. In northern climates many boaters prefer to not leave their electronics installed on the boat over the winter due to concerns about extreme low temperatures. (Dave, you might comment about that if it is a consideration for you in Minnesota.)

Finding some sort of terminal strip or binding post that can accept very small gauge wire is difficult. I am not quite sold on the one shown by Tom, as I think it is somewhat iffy on really small wires, like a AWG-26 wire. In any case, the terminal strip or binding post is not the best approach for a cable you want to remove easily. You have to remove all those individual wires, and later reconnect them in just the right sequence. A connector would take care of both of those problems.

It is too bad that the NMEA has not specified some sort of connector to be used. I think a 9-pin DB-series connector, as commonly used with computer serial data ports, would be a good choice. The connectors are cheap, easily obtained, and not hard to assembly. You could solder up the radio cable to the connector in a standardized manner, and then make all interconnections using mating sockets mounted to some small circuit boat. You'd hard wire the interconnections between devices on the circuit board, perhaps using jumpers.

I have been thinking about laying out a little circuit board like that and fabricating a prototype to see if I like it. How does that sound to you guys?

David Pendleton posted 08-10-2009 08:23 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Jim, I think that sounds like a terrific idea.

And yes, that's why I pull the radio. I pull all my electronics except the RADAR scanner every Fall.

Raymarine used to use a wiring harness with a large connector inline that handled power, NMEA in/out, and an external speaker.

The new Raymarine radios do not. I'm very dissapointed about that.

In-fact, presence of a connector like this will be the prime consideration for my next radio. It would also be nice if manufacturers stopped using hair-like wire guages.

I have a spare Raymarine junction box with the terminal strip similar to what bluewaterpirate posted, so I'll use that for now.

jimh posted 08-10-2009 08:39 PM ET (US)     Profile for jimh  Send Email to jimh     
I think (already) I have to change my recommendation on the connector. The connector has to be a circular connector in order that any hole through which the connector has to pass can be as small as possible. A cheap connector is the MINI-DIN series, which is similar to the so-called PS2 connector used on computer peripherals.
bluewaterpirate posted 08-10-2009 08:54 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
I use 22 gauge connectors to connect the smaller NMEA wire to 22 gauge tinned wire. I use the same color 22 tinned wire to match the NMEA wires. After I connect the NMEA wires to the 22 gauge wire I secure them so they won't move due to the motion of boat. I coat the 22 gaugw wire ends with a small bead od solder then secure them to the terminal screw posts. That way you can remove your equipment whenever you want to.

Tom

David Pendleton posted 08-10-2009 09:50 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Well, I can't find my spare Raytheon Sea-Talk junction box (the one with the terminal strip in it). Dang-it.

I'm breaking out the DigiKey catalog to see what I can find in there.

I think the terminal strip (or junction box) approach would have worked okay. After all, that's how I hook my Raystar 125 to my RADAR/Chartplotter.

I'm also intrigued by these products:

http://www.posi-lock.com/positwist.html

but I haven't located a local source for them yet. It looks like they're on Carquest's line card, so I'll check them out tomorrow.

Thanks for the brainstorming help.


L H G posted 08-11-2009 10:53 AM ET (US)     Profile for L H G    
I use the two, three or four prong flat connectors, which look like trailer connectors, on EVERYTHING in the boat that may have to be removed, or replaced. 20 years, and no failures. These come with pigtails, about 2 bucks at PepBoys for the most commonly used 2-prong versions, and I crimp them on with butt connectors by folding over the thin wire several times.

Recently I had to replace a bilge pump. Just unplugged the old one, cut off the plug, re-crimped it on to the new pump wires, and plugged it back in. Same for radio and GPS/Sonar power leads.

jimh posted 08-11-2009 01:28 PM ET (US)     Profile for jimh  Send Email to jimh     
Browsing through the DIGI-KEY catalog I found that the MINIATURE DIN CONNECTOR (mini-DIN) is a good candidate for connecting small gauge NMEA serial data conductors. The mini-DIN has these attributes:

--very inexpensive, typically less than $1.50

--solder contacts suitable for small 24-AWG or 26-AWG wire

--available as both in-line plug and socket, or receptacle with many mounting options, including circular with retaining nut; I find circular connector mounts to be handy because you can make the hole with a drill; other shapes for connectors require making elaborately shaped cut-outs with nibblers or files

--available in up to 8-contacts

The typical NMEA device will have two or three serial data lines. The receive lines typically are differential pairs (marked + and -) and the transmit lines are typically single-ended with reference to ground. We could configure a 7-pin connector as follows:

PIN - SIGNAL
1 -- NMEA 1 IN (+)
2 -- NMEA 1 IN (-)
3 -- NMEA 1 OUT (+)
4 -- GROUND
5 -- NMEA 2 IN (+)
6 -- NMEA 2 IN (-)
7 -- NMEA 2 OUT

I like the 7-pin because it has a positive keyway to help mate and align the plug and jack. There are also 8 and 9-pin versions, too.

David Pendleton posted 08-11-2009 02:04 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Jim, do you have a part number?
David Pendleton posted 08-11-2009 08:52 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Never mind, Jim.

Here's what I've decided to do: while digging around for my missing SeaTalk junction box, I came across a coil of shielded twisted-pair plenum cable with the pvc jacket.

My radio only has four NMEA leads, two for input, two for output--a perfect application for an RJ11.

So, I'm going to pull out the instrument wire, run the twisted pair, install RJ11's on both the radio and twisted pair, then use a F-F connector to link them.

Space in my hardtop's rigging tube is pretty tight right now. I'm using Ancor's two conductor "instrument" wire to connect the radio, and it's overall gauge is larger than the twisted-pair. This way, I get two more wires in less space than before in case I ever get a plotter that supports position requests.

jimh posted 08-12-2009 08:04 AM ET (US)     Profile for jimh  Send Email to jimh     
Dave--If you use a six-position modular telephone plug with only the center four conductors actually wired (which is what most often is called "RJ-11") be very careful about using adaptors with back-to-back jacks (or female-to-female). Some of those adaptors will not maintain the orientation of the contacts. In telephone use there is not too much concern about polarity of the TIP and RING conductors, and it is common that they are swapped when passed along by some devices such as those extension jacks. Also be careful using any pre-made silk cords with plugs. Some cords flip the polarity, too.
jimh posted 08-12-2009 08:15 AM ET (US)     Profile for jimh  Send Email to jimh     
Larry's technique of buying a pre-molded automotive trailer wiring connector with pig tail conductors and then splicing it onto an existing cable is not a very good solution for connecting NMEA serial data conductors. The typical NMEA serial data conductor is an AWG-24 or perhaps AWG-26 wire. The typical "Pep Boys" auto pre-molded connector comes with rather stiff bare copper AWG-14 wire. Making a splice connection between wires of such radically different sizes is not a good technique. The stiff larger conductor will probably overwork the fragile smaller conductor.

I also am not too fond of using connectors which are pre-molded and have to be spliced onto existing wires. The splice connections are awkward and prone to problems. The splices add bulk to the cable, too. At the connection point you now have four mechanical connections:

--splice---connector--connector--splice---

With a proper connector you have only two connections: connector--connector. There are twice as many mechanical connections to go wrong with the spliced-on connector technique.

A further problem with the connectors that Larry mentions is they are usually a combination of pins and sockets. Any sources of voltage must not be wired to the connector that has an exposed pin, as it risks a short circuit when the connector is not mated.

David Pendleton posted 08-12-2009 03:20 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Jim, I checked my coupler and it is pinned straight-through.

I will also maintain this pin-out when attaching the connectors.

swist posted 08-13-2009 08:43 AM ET (US)     Profile for swist  Send Email to swist     
Is this getting too complicated? I swear I've used tiny little gray wire nuts for such purposes
Chuck Tribolet posted 08-13-2009 01:29 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I built an genderless connector out of two 2-pin connectors.
(think a flat-four trailer connector with only two pins).


Chuck

roloaddict posted 08-14-2009 12:28 AM ET (US)     Profile for roloaddict  Send Email to roloaddict     
I used Molex connectors for 20 years to connect all kinds of devices that would someday need to be removed for service or repair. I even used them on Furuno radar magnatron leads (High Voltage!), because after a few Maggie changes the pulse transformer would fail due to heat damage from the soldering on the posts. They are not weatherproof however.

The little round connector JIMH described was very common on the Trimble Marine GPS's in the 90's and early 2000's. they seemed to work ok and were advertised as weatherproof due to thier O-ring and rubber boot. Nearly all that I messed with were corrosion and water free when opened. Soldering to those little pins at the end of a long install day was a guaranteed finger roaster. The little tug boat company I did work for had 400 or 500 of those Trimbles over the years so someday the Feds may accuse me of trying to hide my identity.

jimh posted 08-14-2009 10:34 PM ET (US)     Profile for jimh  Send Email to jimh     
The funny part of roloaddict's comments is that 20 years ago if you said you were using a Molex connector there was a universal understanding what connector your meant. However, today Molex makes so many different connectors that there no longer is a "Molex connector." There are now about a hundred different varieties.

I do agree that in the way back it was extremely common to use a Molex connector for many low-voltage home brew applications. They were found everywhere.

roloaddict posted 08-14-2009 11:55 PM ET (US)     Profile for roloaddict  Send Email to roloaddict     
True. Somethings like that old Molex and a perhaps a few Whalers still work, even though change has come.
David Pendleton posted 08-15-2009 12:26 AM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
My previous Raymarine (and Raytheon) VHF radios used Molex connectors.

I loved it. I don't know why they switched, but their new wiring layout and options suck.

If I didn't like the radio so much, I'd switch to whomever is using a Molex-like system for wiring connections.

David Pendleton posted 08-16-2009 10:57 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
Finished this over the weekend.

Taped the new STP to the existing instrument wire and pulled it through. Wired up the junction box in the upper e-box, then installed an RJ25 on the other end in the lower e-box.

Finished by installing an RJ11 on the radio. Click, and done.

Disconnnects as easily as your phone. I wish I would have done this last year.

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