Tom wrote:

Thank you gents for the discussion.

Yes, I talked to Lowrance and of course they have a $200.00 (new tranducer
with longer coax) and my installation time is about a day's work. Of course
when you start pulling off panels of a 40 year old boat with flybridge you
will find another day's work.

I don't have a scope but I have a digital volt/ohm meter. I was hoping there
was a method of testing the existing transducer for compatibility.

The plug's ends do not match (male -- female) so I would have to splice to
use the exisiting.

Sounds to me that the most guaranteed way to buy the new product and install
it. But I am a Ham, and more of an Appliance Operator. The formulas you
shown above were most interesting but I didn't understand the theory and the
conclusion.

If I take it to the Marina, wow, that would be another $250.00 costs for
them to install a new tranducer, plus the costs of labor for their chap to
install it. There is nobody at any Marina around here (Southern Ontario
Canada) that would understand what you folks have talked about above and
they would instantly and simply order the new parts and install them. Maybe
installing less quality cables as the ones that are there are gutsy ones and
it is a through hull fitting already in place. In fact all Marina's around
here have very negative reputations for stuff like this.

So if you folks were in the same boat as I am, would you splice it? Would
you be worried about it working incorrectly or the possibility of it
damaging the head? I am not worried about deep water operations, never in
water over 100 feet deep and I believe these are good to 800 feet.

Would you guys simply slice it properly? Job done in an hour. Or take
Lowrance's suggestion and spend the money and time?

Thansk again for very informative and interesting discussion,

Cheers and Best Regards

73s


I certainly would not worry about the old transducer damaging the
equipment. What I would worry about is it working a bit but much less
effectively than the new transducer. Someone produced some data
suggesting the new head needs a 192kHz transducer and your old one being
200kHz (or possibly vice versa). Whether that matters depends how
sharply tuned the transducers are. I would guess that they would *not*
be very compatible but might work a bit. You could actually estimate
how sharply tuned the transducer is by using an impedance bridge with
variable frequency, but if you can't borrow one it would probably be
possible to do measurements with simpler equipment. This would not be
conclusive though. If you can find some published figures for the sound
output bandwidth of this sort of transducer it mght tell you whether to
expect useful results with about 4% mistuning. I suspect they are
actually quite sharply tuned if they are electromechanical, but I don't
even know if this is the case. The alternative being piezoelectric.

Can you temporarily rig the new transducer in a small dinghy and do A to
B comparisons alongside each other, and see whether one is much more
effective?


--
Roger Hayter