Section-g: vhf-dsc Equipment & Communications: Key Topic #49: vhf Controls, Power and Range:

49G1 Which of the following control selections may result in limited receiving range?

A. Setting the squelch control to its maximum level.

B. Setting the squelch control to its minimum level.

C. The power switch is set to the "high" output position, resulting in receiver overloading.

D. Setting the channel selection switch midway between channels 6 and 16.

49G2 At mid-day, what would be the best choice in attempting to communicate with a shore station 15 miles distant?

A. 16 MHz band

B. 156-164 MHz band

C. 12 MHz band

D. 22 MHz band

49G3 Which of the following factors does not normally affect the range of VHF transmissions?

A. Salt water ingress into the antenna coaxial cable.

B. Power level setting.

C. Ionospheric refraction.

D. Vessel antenna height.

49G4 Much longer than normal VHF communications distances are typically caused by:

A. Changing power from 1W to 25 W.

B. Skywave reflections from the D layer.

C. Ionospheric activity in layers F1/F2.

D. Atmospheric ducting or tropospheric propagation.

49G5 Describing VHF transmissions as "line of sight" does not mean:

A. VHF communications are effective only with nearby stations within visual range of the bridge.

B. Vessel antenna height will not affect the radius of propagation.

C. The normal transmission range to a coast station is approximately is 10 NM.

D. Coast station antenna height has no effect on the radius of transmission.

49G6 The effectiveness of VHF communications is maximized by:

A. The adjustment of squelch for maximum receiver sensitivity, setting transmitter power to 1W & selecting an appropriate channel.

B. Appropriate setting of the transmitter power, selecting an appropriate channel & adjustment of squelch for maximum receiver sensitivity.

C. Selecting an appropriate channel, adjustment of squelch for minimum receiver sensitivity & setting transmitter power to 1W.

D. Selecting an appropriate channel, adjustment of squelch for minimum receiver sensitivity, setting transmitter power to 25W.

Answers: 49G1 - A 49G2 - B 49G3 - C 49G4 - D 49G5 - A 49G6 - B

Section-g: vhf-dsc Equipment & Communications: Key Topic #50: vhf Channel System:

50G1 A VHF frequency channel pair of TX 157.200 MHz and RX 161.800 MHz would most likely be:

A. A VTS frequency for VTS – Ship communications.

B. A simplex Public Correspondence Coast Radio Station frequency.

C. A simplex Private Coast Radio Station frequency.

D. A duplex Public Correspondence Coast Radio Station frequency.

50G2 Which channel is utilized for the required Bridge-to-Bridge watch?

A. VHF-FM on Ch-13 in most areas of the continental United States.

B. DSC on Ch-70

C. VHF-FM on Ch-16

D. The vessel's VHF working frequency.

50G3 While conducting routine communications using the wheelhouse VHF with a station 1 mile distant, your recommended power setting would be:

A. 25 watts after dark.

B. 1 watt, day or night.

C. 25 watts during a clear sunny day.

D. 1 watt using DSC at night.

50G4 The USA-INT control on VHF units:

A. Selects duplex operations for U.S. coastal waters and simplex operations in non-U.S. waters, on the "alpha" channels.

B. Ensures that the “alpha” channels are correctly set to duplex for use in U.S. waters & on VTS channels.

C. Changes selected international duplex channels to simplex channels for use in U.S. waters, on the "alpha" channels.

D. Changes selected international simplex channels to duplex channels for use in U.S. waters, on the "alpha" channels.

50G5 The USA-INT control on VHF units:

A. Was made necessary by a desire for more duplex channels in the U.S.

B. Correctly set, will result in duplex operations in U.S. Coastal waters on the "alpha" channels.

C. Correctly set, will result in simplex operations in U.S. Coastal waters on the "alpha" channels.

D. Was made necessary by a desire to convert simplex international channels to duplex channels in the U.S.

50G6 Proper and legal VHF operations require all of these except?

A. The channel must be designated as valid for the nature or type of communications desired.

B. Simplex, duplex and alpha channel modes must be correctly selected.

C. The power level must be appropriately chosen by the operator.

D. The correct bandwidth must be selected by the operator.

Answers: 50G1 - D 50G2 - A 50G3 - B 50G4 - C 50G5 - C 50G6 – D