'Vintage' speed log

[jonathanhsm]

I have a 'vintage' Plastimo speed paddle transducer (circa 1985) with a through hull hole to match, which has never worked.
As you can see the wire coming out is perished.
Anyone know a replacement that would fit the through hull ..I understand Plastimo became Advansea/Navman ?

Alternatively I can get a reading with probes pressed to the relevant core and shielding while spinning the paddle wheel. So I'm wondering if I excavate the wire exit hole if I could solder in new connections.

And if so what co-axial wire would I need ... the current wire is badly corroded. ?

Many thanks

 

[andsarkit]

If it is just a coax the switching must be a reed switch operated by the magnets. (modern ones use a hall effect solid state switch with 3 wires).
The frequency is so low that a coax is not necessary and any cable will work. Coax might help with screening if the pulse affects other nearby instruments.
If you can dig out some of the potting and remake the connections and replace the potting you might be able get it working again. If water has got into the coax it will have wicked along and is likely to have caused further corrosion which will give trouble later on.

 

[jonathanhsm]

Many thanks ... I have cut the top off and can make a clean connection (only two wires) which is working when I spin the paddle so all good. I shall epoxy it all back together again.
Meanwhile the original corroded cable is 3.5mm co ax ... looks pretty similar to RCA speaker wire to me. Also I have a loose end of RG58 aerial cable which would be long enough.
Would either of these work ok ?

 

[andsarkit]

I'm sure almost any cable would work so it is more a choice of physical attributes. The RG58 is quite thick and stiff and might transmit movement to the joint unless you can incorporate some strain relief such as a small cable gland epoxied in the top.
Check your RG58, as some has a solid rather than stranded centre conductor and would not have the necessary flexibility.
Also consider the plug which is probably a phono and needs to be a suitable size for the cable.