Selecting The Frequency - Raymarine L1250DRC Owner's Handbook Manual

5-16
While the HD Series Fishfinder searches in Hunt mode, a constantly changing
'stairstep' pattern is displayed as the sounder switches depths and frequencies.
This situation is most likely to happen while the vessel is travelling at a high
rate of speed.
If you do not wish to view this stairstep hunt pattern, switch to MANUAL
RANGE to turn off Hunt mode. Then, when you reduce speed, return to AUTO
RANGE to continue the hunt for bottom.

Selecting the Frequency

HD Series Fishfinders use dual frequency sonar—50 kHz and 200 kHz—
and can be used in either auto or manual modes.
The fishfinder can automatically select the appropriate frequency, based
on the current display range. As the depth increases while in Auto Fre-
quency mode, the sounder module shifts from 200 kHz to 50 kHz at 250 ft
(80 m). As the depth decreases, the sounder module switches from 50 kHz
to 200 kHz at 150 ft (50 m).
The Auto Frequency setting is also useful for automatically searching for
bottom, as described in Hunt Mode on page 5-15.
Alternatively, you can manually select either frequency, or both frequencies
simultaneously (split frequency). Each is suitable for a particular purpose:
50 kHz Frequency
When using this frequency, the transducer scans a wide area. The 50 kHz
signal penetrates water well, so is good for use in deep water.
200 kHz Frequency
When using this frequency, the transducer scans a narrower area, but produces
a more detailed view. The 200 kHz signal is good for finding fish near the
bottom or close together. It is better for use in shallow water.
Split Frequency
The transducer can operate in both 50 kHz and 200 kHz frequencies at the
same time. If you choose split frequency operation, the scrolling bottom
display is split horizontally. The upper half shows the 200 kHz detailed view
and the lower half shows the 50 kHz image.
➤ To change the frequency:
1. Press the FREQUENCY soft key. The frequency selection soft keys are dis-
FREQUENCY
played.
2. Press the appropriate soft key – 50 KHZ, 200 KHZ or SPLIT. The scrolling bot-
tom is displayed in the selected frequency.
HD Series Fishfinders