Refer to Table 5-2, Chapter 5, to select the proper channel to be used as a working
channel after initial contact Before transmitting on the working channel, make sure
channel selected is not in use.
Hold microphone about 1 inch from the mouth, press and hold PUSH-TO-TALK button on microphone, and
speak into it slowly and distinctly.
When message is complete, release PUSH-TO-TALK button so acknowledgement and incoming messages
can be received. Marine radios cannot receive incoming messages while transmitting. Wait until incoming
message is completed before pressing PUSH-TO-TALK button again to transmit.
10-9.2 Depthfinder operations. This Aqua Probe model 550 digital depthfinder operates like a computer that is
programmed to filter and interpret return signals. It displays only the depth of the strongest, shallowest echo. It does not
display all return signals.
Make sure power cable and transducer cable are firmly installed in bottom of depthfinder unit.
Make sure LIGHT/OFF/ON switch (Figure 10-5) is in center OFF position.
All other switches must be in down position.
Set SENSITIVITY and SHALLOW alarm knobs to minimum settings by rotating fully counterclockwise.
Turn power on by turning switch to ON during daylight and to LIGHT during darkness. Liquid crystal display will
come on. (If SENSITIVITY switch is set on minimum, it will show a logo and display "No Echo" in lower left
comer.) If boat is over a very hard packed sandy or rock bottom in shallow water, it may receive enough return
signal even at minimum settings to provide a depth reading.
To set SENSITIVITY control, slowly rotate control clockwise to the point where the water depth starts to be
displayed. "No echo" indication will disappear and water depth will be displayed. This is sensitivity threshold.
Continue to rotate control clockwise until display shows two more gradations above threshold.
Select depthfinding range by pushing 2'-99'/4'-499' switch up to shallow range (2 ft to 99 ft).
Make sure update rate on SLOW/FAST switch is set to FAST.
Make sure DEEP ON/OFF switch is in OFF (down) position.
k Turn SHALLOW ON/OFF switch to ON by moving toggle switch up.
Turn ALARM SET/DEPTH switch to ALARM SET by moving toggle switch up.
Adjust SHALLOW knob slowly until liquid crystal display shows 06.0 feet (depth of outboard when boat is loaded
plus safety factor). Shallow alarm may be set to alert operator to any desired depth within range selected for
finder to measure.
In using shallow alarm system and setting depth for alarm to sound, remember
that depthfinder's transducer Is mounted on the stern. Although It sends and
receives signals In a cone shape with transducer at the top of the cone, alarm
system Is NOT foolproof at predicting water depth in FRONT of the boat This Is
especially true when the boat Is moving fast
For additional Information on depthfinder operations, read pages 9 thru 14 of the
Aqua Probe Owner's Handbook In Appendix B TM 55-1930-209-14 &P-17.
Move ALARM SET/DEPTH switch to down position and display will again indicate depth beneath the boat.
Set deep alarm by turning off shallow alarm and following these procedures for setting deep alarm. Then, with
deep alarm on, again turn shallow alarm on. Now both shallow and deep alarms are operating.