Ground Fishing Fish Finder Question

[rnorman3]

Hi, I have a Garmin 431S fish finder with a "dual beam transducer". The description on the package is "frequency is 80/200Hz. Beam width is 45/15 dual beam." I'm catching medium sized cod at about 100ft of water. The only settings available from the menus are narrow or wide. The manual says if you have a dual frequency transducer you should be able to see menu option "split frequency". Anyone else have this finder? Same issue?

Thanks!

 

[dingbat]

Re: Ground Fishing Fish Finder Question

Your confusing "dual frequency" with a "dual beam" transducers. Two different animals. Can't split frequencies in a dual beam transducer

 

[rnorman3]

Re: Ground Fishing Fish Finder Question

Thanks dingbat. But doesn't the 80/200Hz mean dual frequency? if not why is it listed 2 frequencies?

 

[dingbat]

Re: Ground Fishing Fish Finder Question

All transducers put out a 80 kHz signal as a side affect. A 50/200kHz transducer would filter it out as noise, but a 80/200 kHz dual beam transducer actually listens for the 80kHZ returns.

So... you basically have a 200kHz transducer that takes into account the always present 80 kHz signal. You can't select between the two because they are one and the same. The dual beam gives you a "larger" cone angle at the expense of depth.