outboard interference

EddieBremner

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Hi Guys , I've recently replaced a four stroke 5 hp honda outboard with its 6hp2cyl brother, only the new one interferes with my depth sounder, (nasa clipper) only when the charging cable is connected, The engine and transducer are well apart and wiring only comes into contact at the batt. Anybody heard of similar faults, and any ideas on supression where to obtain and where to fit?
 

simonfraser

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car audio systems suffer from this when all the parts are not earthed at the same point, might be worth while checking yours before spending money on fancy bits.
 

William_H

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If you need to go to a supressor of some sort on both the charger lead near the engine (but on the battery side of the rectifier box) and or on the power lead to the depth sounder then these can be made quite cheaply or bought from electronics or car radio supplier.
To make the inductor which connects in series with the power lead you need a ferrite core. You can use the black aerial rod from an old transistor radio or you can use a toroid (doughnut shaped ring with wires wrapped around the ferrite from an old computer power supply. Evan an old key board may have small torroids with the wires wrapped thro0ugh or around a torroid. You need to have wire which will happily carry the current of your device or charger. Wrap the wire around the rod or through the torroid and around and through again as many times as you can fit on. If the torroid is tiny you can go on to another torroid and another.
This inductance provides a choke to stop the high frequency pulses getting through. A capacitor is then connected from the battery line to the negative to bypass the high frequency pulses. These come from an old radio or bought new for peanuts from a radio parts supplier. You need .1 microfarrad also called 100 nanofarrad rated at more than 50 volts. ( anywhere in the range .01 to 1 microfarrad will do. basically the more the better. In the case of the depth sounder this should be connected on the sounder side of the inductor to negative or in the case of the charger on the motor (rectifier) side of the inductor. The fuse in each case should be closer to the battery than the suppressor components to protect in case of wires touching etc. I hope this may help to solve your problem. good luck olewill
 

William_H

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PS as a simple fix you could delete the capacitor and just wind the power lead excess around a ferrite rod from an old transistor radio and see if it helps. several turns may be enough. (on one or both of o/b lead and sounder lead. olewill
 
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