In article ,
Jack Erbes wrote:

That may be bad advice Larry.

Airmar is the major supplier of transducers for most of the brands on
the market. And many of the Airmar transducers come with installation
instructions that tell you not to cut the cable.

And they also warn you that doing it will void the warranty.

You can read it about it here in a typical installation guide:

http://www.airmartechnology.com/uplo.../17-006-01.pdf

I'm thinking that shortening the cable could upset a resonant circuit
and that is not a good thing, right?

Jack

Not really relevant in Depth Sounder Transducer design. Most Sounders
at using LOWER Frequencies than 500 Khz, and the difference in cable
length would only be a very small fraction of a Wavelength, at that
frequency.
The REAL Reason for that Statement, is to keep uneducated folks from
messing up the splice, and then asking the OEM, to replace it for Free,
because it doesn't work anymore.
I have spiced thousands of Transducer Cables, over the years, rather
than running a new one down from the Bridge, when replacing a blown
Transducer. It is a LOT cheaper than Hiring a Carpenter, Electrician,
and Shipfitter, just to pull all the Paneling, Raceway covers, etc, to
run a new Transducer Cable. You splice your RF Cables all the time,
Transducer Cables are exactly the same idea, except usually they are
Differential Loads, (Two wires and Ground/Shield) and significantly
lower in frequency. Attenuation in the splice is linearly related to
Frequency, and at sub 500 Khz is NOT a significant loss. SWR is also
not significant unless you cable is a couple of hundred Meters Long.
It is always nice to give the Output Resonant Circuit a Tweak, after
messing with the Transducer, Cable, etc, and peak it up using an
O-Scope across the Transducer Output of the Sounder. That ensures
that your matched to the Transducer Load, and you can also tweak
the first Receiver Resonator for Maximum Return signal at the same time.
Usually it makes less than 1 or 2 DB difference.

--
Bruce in alaska
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