APPENDIX A — Technical specifications
Table 8: 491 technical specifications
Performance characteristics
Frequencies | 50 and 200 kHz |
|
|
Output power | 1000 watts with |
| 600 watts with |
|
|
Pulse lengths | 0.1 to 2 ms |
|
|
Pulse repetition rate | 30 to 600 pulses/min |
|
|
Alarms | Fish, bottom, and temperature |
|
|
Update rate | 10 Hz maximum (depends on water depth) |
| (up to 20Hz when used with the Northstar |
| 6000i) |
|
|
Zoom modes | Marker, bottom lock, bottom lock/center, |
| bottom |
|
|
Auto modes | Fishing or cruising |
|
|
Navigation data | Shown on bottom of screen |
|
|
Display modes | Single/dual frequency, |
| zoom modes, |
|
|
Physical characteristics |
|
|
|
Dimensions | 8.78 x 7.22 x 2.35 inches (including back- |
| plate) |
|
|
Weight | 2 pounds |
|
|
Environmental characteristics | |
|
|
Temperature | |
| |
|
|
Standards | Waterproof, sealed design meets the follow- |
| ing: EN60529 IP65; EN60945 emissions; CE |
|
|
Electrical characteristics |
|
|
|
| 8 to 36 VDC, 8 watts, reverse polarity and |
| overvoltage protection |
| Transducer outputs protected against open |
| circuit/short circuit |
|
|
491 INSTALLATION MANUAL Revision A | PAGE 27 |
