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-   -   Depth Transducer (http://www.sailnet.com/forums/electronics/86318-depth-transducer.html)

Vundakid 04-17-2012 02:43 AM

Depth Transducer
 
Hi
I have a thru hull transducer that is in a very difficult place to replace. It is circa early '70s and was hooked to a Raytheon Fathometer DE-738L. Is there a way to test it? Can it be used with a new Standard Horizon chartplotter?

Thanks
Tom

dacap06 04-17-2012 08:46 AM

Re: Depth Transducer
 
I don't know the answer to your question since I don't know your specific parts, but for the life of me I don't see why you would want to reuse the old sensor. From the technical perspective this is not a good way to save time and money.

If you really want to pursue this line of thought, here are the things you will need to examine and consider.

-- What transmit frequency or frequencies does the new head unit use? Can the sensor accept those frequencies? These frequencies are typically several hundred kilohertz, which is high enough that you need to take R/F effects into account (important in cabling).

-- What signal amplitude (voltage) and current does the head unit provide? Can the transduce handle it?

-- What are the sensitivity ratings of the two transducers? Are they similar? If they are not you may not see the bottom at all or could get strange, inconsistent readings from echoes.

-- What about fittings for the connecting cable? Are they they common or will you need to buy a custom cable to connect them?

-- And speaking of cables, what coax is used in the new and old system? The two cable impedance ratings will tell you the R/F impedance of the transducer and the head unit (specs that often are not listed on data sheets). Do they have the same impedance per meter rating? Impedance mismatches in the R/F realm will cause signal reflections at one end or the other (transducer or head unit, whichever doesn't match the impedance of the cable you use). R/F reflections that are bad enough will burn out the output transistors of the signal generating circuit (not to mention maybe giving strange readings).

Good luck!

DaCAP


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