cut transducer cable
- Thread starter keithshunter
- Start date
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You should be able to cut and reconnect so long as the length does not change. See the following link. Especially about calling the manufacturer with the question.
http://www.bsacforum.co.uk/forums/showthread.php?t=11694
http://www.bsacforum.co.uk/forums/showthread.php?t=11694
What kind of transducer is it? If it is a depth finder operating at 200 Khz, skill, care and the right type of connector are going to be needed. If it is a speed/temperature unit then as long long as the connection is good and watertight it will work.
John Brecher
John Brecher
Yes, no, maybe. It depends on the transducer and more importantly the skill of the splicer. Almost every manufacturer will void the warrantee if you splice the cable. If it gets wet at the splice it will probably fail or at least not give proper readings. If you cut the shield you could have RF issues. I have seen some work until the transducer failed and others never work properly after being spliced. Chuck
Chuck, Thanks for the great answer. The first response I got was the word no. It did not satisfy my curiosity because I had wondered if maybe the cable was indeed shielded. If I do end up cutting to splice and find it shielded, I will probably just replace the whole length with comparable cable.
Good luck keith. Most braided shielding has been replaced by a thin layer of foil in transducer cables. You could make the splice and see how it works and if you have problems, replace it. Most don't have RF problems if they don't have an HF radio or some other piece of equipment that generates the RF or if you don't run that cable near any high voltage wiring. Chuck
I did it in 2001 to my Raymarine unit. The sender went bad and it was almost impossible to run a new cable in my 51 footer. I cut it 2 feet away from the transducer and spliced it. Soldered. added foil and heat shrink. Has worked for 9 years of cruising in the Caribbean with no problems.
Re: cut transducer cable - An explanation
The transducer cable represents a capacitance and is part of a tuned circuit which includes the transducer itself. The intention of the design is to get this circuit to resonate at the transducer frequency. Shortening the cable will reduce this capacitance and put the circuit off tune - however - this tuning is not particularly critical and a small percentage (couple of inches) cut off the cable should only have a small effect on the power transmitted or on the receiver sensitivity. So the losses could be unnoticeable. Please note the italics.
Of course it is sudden death if any water gets into the cable and cutting the cable is bad practice really.
The above does not apply to sounders which send 12V to the transducer which then it does its own thing and only sends back NMEA signals to the instrument.
The transducer cable represents a capacitance and is part of a tuned circuit which includes the transducer itself. The intention of the design is to get this circuit to resonate at the transducer frequency. Shortening the cable will reduce this capacitance and put the circuit off tune - however - this tuning is not particularly critical and a small percentage (couple of inches) cut off the cable should only have a small effect on the power transmitted or on the receiver sensitivity. So the losses could be unnoticeable. Please note the italics.
Of course it is sudden death if any water gets into the cable and cutting the cable is bad practice really.
The above does not apply to sounders which send 12V to the transducer which then it does its own thing and only sends back NMEA signals to the instrument.
No Problem
I conducted many years of ultrasonic transducer research and development for Milltroncis Limited (still the world's best industrial ultrasonic echo-ranging equipment ever made).
Durng that time, I spliced 100's of transducer cables. (I do the same thing for audio, microwave, and any coax.)
A (proper) splice will cause about a 1/10 dB (negligible) loss in signal strength. (1/2 dB in microwave cable but still not that significant.) Much lower loss than a male x male coupler and two female connectors.
Most properly installed depthsounders will read their maximum range on a hard bottom. (ie They have power to spare.)
Done poorly, the splice may be prone to failure.
Done properly, the splice can be stronger than the cable itself.
Splicing Procedure (assuming coax with foil shield and drain vs all over braided shield):
1. Cut the cable, route as required.
2. Slide a 2", 3" and 4" piece of heat shrink tubing (2-3 times jacket diameter) over one bitter end.
3. On both bitter ends, cut about 1.25" of outer jacket from the cable (being careful not to cut the foil or core dielectric). (If you bend the cable sharply (but not kinked) and nick the jacket with a utility knife, it will seperate easily.)
4. Fold back the drain and foil.
5. Cut about 1" of the dielectric insulator (prolly white foamy plastic) from the core.
6. Prepare a western union splice on the core conductor. (google)
7. Ensure the splice is twisted very tight, and neither core is sticking out making a sharp point.
8. Sweat (solder) the splice, taking care not to melt the dielectric insulator.
9. Make the same soldered western union splice on the drain (or shield).
10. Wind several turns of electrical tape around the core splice to build up the diameter the same as the original dielelctric insulator.
11. Apply silicone sealant (RTV) over the taped splice.
12. Overlap the foil over the silcone.
13. Wind several turns over the foil covered core splice and drain splice, building up the diameter equal to the outer jacket.
14. Apply silicone sealant over the taped splice.
15. In turn slide each heat shrink tubing jacket (smallest first) over the splice, shrink (heat gun) and apply silicone sealant before the next length of tubing.
If you have an all over braided shield the procedure is about the same, but you unbraid the shiled back to the outer jacket cut, twist the strands together, and then treat it like a drain wire. The splice will be a little more susceptible to EMI, but as long as you keep it 6" away from other wiring, it won't be a problem.
With reasonable skill, these splices will last forever and never cause a problem, even if allowed to lay in a bilge (though not recommended).
Pre-gooped tubing can be used but I prefer dry tubing with my own RTV, so I don't slide it off running the tubing down the cable.
This may read complicated, but it's really easy if you are half handy with a soldering iron.
Practice a couple times on a spare length of coax cable before doing the real thing to build confidence and improve skill.
As long as you make a good, waterproof splice, and don't shorten the cable a significant amount it will work like a charm.
I conducted many years of ultrasonic transducer research and development for Milltroncis Limited (still the world's best industrial ultrasonic echo-ranging equipment ever made).
Durng that time, I spliced 100's of transducer cables. (I do the same thing for audio, microwave, and any coax.)
A (proper) splice will cause about a 1/10 dB (negligible) loss in signal strength. (1/2 dB in microwave cable but still not that significant.) Much lower loss than a male x male coupler and two female connectors.
Most properly installed depthsounders will read their maximum range on a hard bottom. (ie They have power to spare.)
Done poorly, the splice may be prone to failure.
Done properly, the splice can be stronger than the cable itself.
Splicing Procedure (assuming coax with foil shield and drain vs all over braided shield):
1. Cut the cable, route as required.
2. Slide a 2", 3" and 4" piece of heat shrink tubing (2-3 times jacket diameter) over one bitter end.
3. On both bitter ends, cut about 1.25" of outer jacket from the cable (being careful not to cut the foil or core dielectric). (If you bend the cable sharply (but not kinked) and nick the jacket with a utility knife, it will seperate easily.)
4. Fold back the drain and foil.
5. Cut about 1" of the dielectric insulator (prolly white foamy plastic) from the core.
6. Prepare a western union splice on the core conductor. (google)
7. Ensure the splice is twisted very tight, and neither core is sticking out making a sharp point.
8. Sweat (solder) the splice, taking care not to melt the dielectric insulator.
9. Make the same soldered western union splice on the drain (or shield).
10. Wind several turns of electrical tape around the core splice to build up the diameter the same as the original dielelctric insulator.
11. Apply silicone sealant (RTV) over the taped splice.
12. Overlap the foil over the silcone.
13. Wind several turns over the foil covered core splice and drain splice, building up the diameter equal to the outer jacket.
14. Apply silicone sealant over the taped splice.
15. In turn slide each heat shrink tubing jacket (smallest first) over the splice, shrink (heat gun) and apply silicone sealant before the next length of tubing.
If you have an all over braided shield the procedure is about the same, but you unbraid the shiled back to the outer jacket cut, twist the strands together, and then treat it like a drain wire. The splice will be a little more susceptible to EMI, but as long as you keep it 6" away from other wiring, it won't be a problem.
With reasonable skill, these splices will last forever and never cause a problem, even if allowed to lay in a bilge (though not recommended).
Pre-gooped tubing can be used but I prefer dry tubing with my own RTV, so I don't slide it off running the tubing down the cable.
This may read complicated, but it's really easy if you are half handy with a soldering iron.
Practice a couple times on a spare length of coax cable before doing the real thing to build confidence and improve skill.
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