Furuno CH-300 Operator's Manual page 22

1. OPERATIONAL OVERVIEW
To use the mix display effectively, it is important that the gain for both the low and high
frequencies is set properly. When searching for young fish such as whitebait, follow the
procedure below. For detailed information about gain adjustment, see the next section.
Gain adjustment
1. Adjust the high-frequency gain while observing targeted fish.
2. While observing the mix display, set the low-frequency gain to 0 and gradually raise it
just until echoes from adult fish disappear from the mix display.
3. While observing the echoes from young fish on the mix display, readjust the
low-frequency gain in order to distinguish young fish. When the echoes from young fish
are weak, lower the low-frequency gain. If adult fish appear, raise the low-frequency
gain. (Rule of thumb: For whitebait, low-frequency gain is set 3-4 steps lower than
high-frequency gain.)
To activate the mix mode, press the MIX key. How to display the mix display depends on the
display mode in use.
Single-frequency display or combination display (other than vertical scan
combination): Use the MIX key to switch between the mix display and the single-frequency
display alternately.
Dual-frequency display: Use the MIX key to switch between the mix display and the
dual-frequency display alternately.
LOW-FREQ.
DISPLAY
Combination display (vertical scan combination:
Main window is active: The MIX key changes the frequency of the main window from low to
high alternately.
Sub window is active: The MIX key changes the frequency of the sub window from low to
high alternately.
To switch between main and sub windows use the MAIN/SUB key.
1-12
MIX key
HIGH-FREQ.
DISPLAY
How the MIX key works in dual-frequency mode
HIGH-FREQ. MIX
DISPLAY DISPLAY