Cutting depth sounder lead?

[Stemar]

The permanent installation of my Target depth sounder (temporary for the past two years /forums/images/graemlins/blush.gif) requires a connector in the transducer lead and the one that's there is in the wrong place.

As long as I don't shorten the lead, is there likely to be any problem putting one in? I'm thinking about a bnc type.

The Target log impellor and Garmin GPS antenna will also need connections where there aren't at the moment, am I right in thinking that these won't be a problem?

I am thinking of using soldered connections which won't be under any mechanical strain.

One last (stupid?)) question. It'd be much easier to use the same connecters for all three, but if I do, Sod's law says that sooner or later, someone will connect them up wrong. Are there any permutations of GPS antenna, log impellor and depth transducer leads that can cause damage if mixed up?

 

[simonfraser]

cut and solder is fine, i've done this for the above with no probs

same connectors, you are asking for trouble, unless you are very smart of course ;-)

cut the existing leads before the connectors, put it through the holes and solder the leads back together again, no need to buy new connectors ?

 

[Finnsailing]

Marine connectors are available from RS and Farnell Online ( Let me know if you need the part number ) . If you use a 3 pin and 2 pin and a 2 pin the wrong way round you get three connectors you cannot connect the wrong way. I cut the cable on my AIRMAR transducer and removed about a meter does not seem to make a difference boat still runs aground when it says 2 meters on display ( will remember to wind keel up next time ) /forums/images/graemlins/cool.gif

 

[Finnsailing]

If you are going to just cut the wires use some heat shrink sleaving over the joint its beter than tape . Comes in different sizes to ( MAPLINS )

 

[Stemar]

The plan is to have an easily removed instrument pod that I can put below when not in use and take home when I'm not on board. That way I hope to keep the light fingered brigade at bay.

Since, as I understand it, only the depth sounder is active, I could use a different type of connector for that and use BNC for the other signal leads on the basis that signal strength from the GPS antenna and log impellor will be too low to do any damage, and if I do mix them up they just won't work until I swap them round.

Any thoughts anyone?

 

[alan]

Not familiar with the instruments that you have, but you are assuming (or maybe you already know) that there is just one signal wire and a shield.
For instance the GPS antennas that I have come across are in fact antenna/receivers that output NMEA signals as well as requiring power and ground, thus there are at least four wires needed. The log also requires more than just one conductor and shield I would think.

Just a thought but maybe you should (if you have not already done so) check exactly the number of conductors each unit needs and then select the connectors accordingly.

Alan.

 

[claudio]

The GPS is active too. The antenna has an amplifier built in. Power is supplied through the signal cable. Sending the depth sounder pulse to the GPS antenna may destroy the amplifier. I would use connectors suitable for purpose, as another poster mentioned have a look at RS components rswww.com, there are plenty there.

 

[Stemar]

The GPS is a Garmin 128, which, from memory (everything's on the boat at the moment) has a BNC type connector on the back for the antenna. NMEA is done by the instrument, but I'll ignore it as I have no use for it at present.

The other two have co-ax leads with TV-type plugs and sockets. These, unfortunately, are too close to the instuments to be useful, so I was going to hide them in the pod.

I haven't mentioned the 12v feed as I'm quite happy with my plans for it.

 

[steve_l]

Be careful about cutting the lead. The characteristic impedance of the cable is important in NASA echo-sounders. So even cutting the cable and connecting again with connectors could change this, leading to inaccuracy in the reading.
Unfortunately I don't know what impedance the cable is, but to reduce the possible error the connectors should at least be the same impedance (50ohm connectors for 50ohm cable, 75 for 75).

Hope this helps...

-steve-

 

[eddieperkins]

Use coloured heat shrink to colour code your cables. You can also put connectors on opposit ways (Male Female) - you would not be able to fit two males together accidently - or two females for that matter. I have a connector in my Furuno GPS 30 with no problems. Also have a factory fitted connector in the echo sounder (Nasa) so I would think it should be fine. Good quality connectors are called for, not ones from a TV store, especially if they are in potential damp places.
Eddie