Eagle FISHMARK 640C, Installation And Operation Instructions Manual

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68
Frequency (Change Transducer Frequency)
(SeaFinder unit only)
The SeaFinder transducer operates with both 200 kHz and 50 kHz. The
200 kHz frequency has a 12
°
cone angle and the 50 kHz frequency has a
35
°
cone angle.
The default frequency is 200 kHz which is best for shallow water (about
300 feet or less) conditions. This frequency is best for about 80 percent
of the fresh and salt water sport fishing applications. When you get into
very deep salt water, 300 feet or deeper, the 50 kHz frequency is the
best choice.
The 200 kHz transducer will give you better detail and definition, but
less depth penetration. The 50 kHz transducer will give you greater
depth penetration, but a little less detail and less definition. Remem-
ber, all sonar units typically read deeper in fresh water than in salt wa-
ter.
There is a common exception to these rules of thumb. Some fishermen
on freshwater lakes (or the ocean) using downriggers like to see them
on the sonar. In many of those cases, you will see a 50 kHz transducer
frequency in use because the wider cone angle lets them watch the bait.
Sonar Features menu with a frequency of 200 kHz selected.