BNC Connectors for Transducer Wiring

[Stu Jackson]

The connector between my speedo transducer's 10 foot wire and the long wire back to the cockpit display has 'died' from being "hidden" and underwater in the bilge for the past 29 years.

It is a BNC connector. Datamarine SX120. I have been attempting to get the two parts part for the past few days, using all the "usual suspects" to no avail.

It appears that I will need to cut both wires and install new connectors.

I am aware that there are BNC connector tools available, although the ones on Radio Shack's website have gotten poor reviews.

I will contact DMI tomorrow to determine if it is a 50 or 75 ohm connector and what the wire size is.

I would appreciate any suggestions for a proper BNC connector tool and source that actually works.

[KWKloeber]

Stu. Stu, Stu...... don'tcha know that water and electrons don't mix!  (or shouldn't)  

There's a couple ways to go.... the crimp (hex) style, the compression style (like all the cable companies use for F connectors) and the myriad of push on, solder, non-solder, twist-on, etc. connectors.

I'd go with compression type -- seems to be state of the art.  Well at least state of the times anyway.

ProsKit had compression terminals and the compression tools -- I have used and sold other ProsKit stuff (what I had was good quality, though not BNC.)   

http://www.proskit.com/connectors/coaxial?sort=20a&alpha_filter_id=66
http://www.proskit.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=bnc+compression

Pros also carries the crimp frames and dies for different BNC barrel sizes (hex style crimp.)

http://www.proskit.com/crimpers/frames   The luna and pro frames accept interchangeable dies below:
http://www.proskit.com/crimpers/dies?sort=20a&page=1

ACTUALLY, the ProsKit dies, fit the inexpensive HF crimper frame and work perfectly!
http://www.harborfreight.com/ratcheting-crimping-tool-97420.html

This is the best deal in a quality crimper frame (actually made by the same people for ProsKit Luna series:
http://www.all-spec.com/products/VDV212803.html   
And accepts all the ProsKit dies.


If you go the compression type, look for "sealtite" series -- they are pretty good and the compression tools are reasonable...

Let's see what I can find...
Here you go...  10-packs aren't too bad.  Do you know -- RG6...  RG59...  cable?

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dtools&field-keywords=%22paladin+bnc+connector&rh=n%3A228013%2Ck%3A%22paladin+bnc+connector

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dtools&field-keywords=bnc+sealtite&rh=n%3A228013%2Ck%3Abnc+sealtite


I think the two big boxes carry 'sealtite' in the F-style, maybe also in the BNCs?  I guess you'll have to use a barrel connector if you can't find the mating connectors.

A new connector; some heat shrink --- and it will go another 50 years in your bilge! 


Ken

[Stu Jackson]

Thanks, Ken, that's a great bunch of info.

I don't know what the wire is, hence my call to DMI tomorrow.  It's very thin coax, only 1/8" or so diameter with the insulation.

Have you had any success of just cutting and splicing rather than trying to install connectors, or does that screw up the dialectric and the signal?

I would normally not allow this kind of thing (connector in the bilge) but I simply didn't know it was there.  When doing my research and homework, I learned there is a connector from the DMI website.  One could figure the factory would have installed it way up forward near the transducer, or at least somewhere you could see it.  But I guess Paco was busy on Friday.

Actually, it'd be great if I could find someone here in the SF Bay area who has a bnc crimper and knows how to use it.   

[Craig Illman]

Stu - Is it just a speed with no depth? I butt spliced the five wires for my replacement Airmar speed/temp sensor to my Standard Horizon display. Airmar has wiring diagrams for many display manufacturers. The requirements for splicing a depth transducer are beyond my current level of knowledge.

Craig

[KWKloeber]

Stu,

How about "my box? -- might be easier than soldering (though you can.)  
I doubt you would have any interference issues --- and only if became an issue --- then spray glue pcs of alum foil on the inside walls, back, cover.  

If you solder, then the next thing is you'll need to replace the pickup.... and you're back to the beginning.  

Drop an email or PM here, they have BNC connectors --and appear to know all about DMI.

http://www.navigatorschoice.com/index.php?main_page=contact_us


Soldering:

light light heat and use heat sinks to protect the conductor insulation.

Instead of the twist-the-conductor/then solder method, I first use tinned, non-insulated crimps (Radio Shack has 24-26 AWG) followed up w/ solder -- if the cable/conductor/dielectric size makes it possible.  Then heat shrink tubing over that, extended onto the dielectric.

Solder the ground/shield so it's continuous, followed by HST built up to the cable OD.   For physical protection and to prevent any work hardening of the conductors, I use mil-spec (heavy wall) HST over the entire joint.

If you're concerned about signal contamination, wrap a narrow strip of alum foil around the heat-shrunk center conductor (underneath the soldered ground/shield wire so both are in contact.)  Then HST the whole shebang,m I would then cover all w/ milc-spec HST for protection and triple moisture barrier.

ken

[Stu Jackson]

If you solder, then the next thing is you'll need to replace the pickup.... and you're back to the beginning.  

Ken, why would that be?

Thanks for the other info.

Craig, it's just a straight knotmeter, DM  SX-120L.

[Craig Illman]

Stu - Look at this page? http://faq.airmar.com/index.php?action=artikel&cat=1&id=240&artlang=en

[KWKloeber]

If you solder, then the next thing is you'll need to replace the pickup.... and you're back to the beginning.  

Ken, why would that be?

Thanks for the other info.

Craig, it's just a straight knotmeter, DM  SX-120L.

Because you won't have a M-F plug there to disconnect/replace the sender -- you're back to having to replace BNCs anyway, or resolder....

Any progress?
Have you thought about "my box"?   That might be the simplest and quickest?  Easy to crimp on a couple mini terminal per RC's
DIY, I have the frame and that die, and it works great.  Add one to the toy box. 

Ken

[Stu Jackson]

Because you won't have a M-F plug there to disconnect/replace the sender -- you're back to having to replace BNCs anyway, or resolder....

Any progress?

Have you thought about "my box"?   That might be the simplest and quickest?  Easy to crimp on a couple mini terminal per RC's

DIY, I have the frame and that die, and it works great.  Add one to the toy box. 

Ken

I stopped in a ham radio place at the suggestion of some folks over on co.com.  It's RG 58 cable.  He gave me a male BNC connector for free, but did not have female BNC's, since I guess those are always at the back of the radios and not on the ends of the wire in the "ham radio world."  This is consistent with the DMI instructions (for a new transducer): 

When you remove the old SX-120 you will find it is wired exactly the same as the new one, meaning there will be the same 10' cable with a female BNC on the end. There is an interconnect cable between your knotmeter and speed  sensor [SX-120]. The interconnect cable consist of a 30' run of coax cable with male BNC connectors on each end. One end mates with your knotmeter,  the other end mates with the SX-120. No splicing, adapters or cutting  needed. Just disconnect the old one, connect the new one and you are done.

I went to the marine electronic store at the suggestion of the ham radio gentleman, and the folks there said just splice it by un-braiding the outer wire, like the photo below.

It seems easier than buying a once-in-a-lifetime use tool.  I think Ken's BOX idea will work.

It's going to be brain-salad-surgery to do this with the wires on the saloon sole.

[KWKloeber]

Because you won't have a M-F plug there to disconnect/replace the sender -- you're back to having to replace BNCs anyway, or resolder....

Any progress?

Have you thought about "my box"?   That might be the simplest and quickest?  Easy to crimp on a couple mini terminal per RC's

DIY, I have the frame and that die, and it works great.  Add one to the toy box. 

Ken

I stopped in a ham radio place at the suggestion of some folks over on co.com.  It's RG 58 cable.  He gave me a male BNC connector for free, but did not have female BNC's, since I guess those are always at the back of the radios and not on the ends of the wire in the "ham radio world."  This is consistent with the DMI instructions (for a new transducer): 

When you remove the old SX-120 you will find it is wired exactly the same as the new one, meaning there will be the same 10' cable with a female BNC on the end. There is an interconnect cable between your knotmeter and speed  sensor [SX-120]. The interconnect cable consist of a 30' run of coax cable with male BNC connectors on each end. One end mates with your knotmeter, the other end mates with the SX-120. No splicing, adapters or cutting  needed. Just disconnect the old one, connect the new one and you are done.

I went to the marine electronic store at the suggestion of the ham radio gentleman, and the folks there said just splice it by un-braiding the outer wire, like the photo below.

It seems easier than buying a once-in-a-lifetime use tool.  I think Ken's BOX idea will work.

It's going to be brain-salad-surgery to do this with the wires on the saloon sole.

Stu,

Box: Crimp, solder on terminals and use a term strip, yah mean? 
With that waterproof box, it could LIVE in your bilge.   

Were the BNCs you got a crimp, compression, or twist-on?  I believe I have seen FM to FM barrel couplings readily available.

Since it's just RG-59 cable  as an option I would be tempted to first try using just two F-type Male connectors and a FM- FM barrel coupling between them, instead of the BNCs.   And heat shrink it up super waterproof.  The F will transpit the singnal same as a BNC will.

Ken

[Stu Jackson]

Since it's just RG-59 cable  as an option I would be tempted to first try using just two F-type Male connectors and a FM- FM barrel coupling between them, instead of the BNCs.   And heat shrink it up super waterproof.  The F will transmit the signal same as a BNC will.

That may be a much more attractive situation.  I'll see if I can get those from the ham radio store.

[KWKloeber]

Since it's just RG-59 cable  as an option I would be tempted to first try using just two F-type Male connectors and a FM- FM barrel coupling between them, instead of the BNCs.   And heat shrink it up super waterproof.  The F will transmit the signal same as a BNC will.

That may be a much more attractive situation.  I'll see if I can get those from the ham radio store.

That coupling-up, could still be made inside, rather than do away with it, the box.  Instead of needing to heat shrunk to moisture-tight it all.

kk

[Stu Jackson]

I found a BNC to BNC connector:  https://www.youtube.com/watch?v=aoRwPPrY9z8  See minute 3:45.

There are also twist-on BNC connectors so I don't have to purchase a crimper.

Looks like it's worth getting a stripper instead of trying to strip the insulation back with a box 8cutter - that RG58 is too small for even my tired old eyes to see without a magnifying glass!!!

[KWKloeber]

I found a BNC to BNC connector:  https://www.youtube.com/watch?v=aoRwPPrY9z8  See minute 3:45.

There are also twist-on BNC connectors so I don't have to purchase a crimper.

Looks like it's worth getting a stripper instead of trying to strip the insulation back with a box cutter - that RG59 is too small for even my tired old eyes to see without a magnifying glass!!!

Here's the coax striper that I use...  works fine for the little I do (mostly reran some Time Warner cable at the new house).
http://www.harborfreight.com/rotary-coaxial-cable-stripper-98953.html

And this is the compression tool I use for RG59, RG6.   Works perfectly.  I bought better seal-tite terminals also.
http://www.harborfreight.com/coaxial-cable-compression-tool-95862.html

I would guess that a "seal-tite" compression type would be better than twist-on, and slightly better than crimp-on, but 'EASY' is worth trying first for sure.

Female - Female couplers are all over eBay and Amazon.  RShack also.
http://www.radioshack.com/gold-plated-bnc-female-to-female-coupler/2780119.html#.VVObQflViko


Ken

[Stu Jackson]

Thanks, Ken.  I'm glad the "real world" (at least YOURS  ) reflects what I've learned from YouTube. 

Like ATM machines, microwave ovens and autopilots, how did we ever live without it?