The permanent magnetic field that surrounds a traveling-wave tube (TWT) is intended to:

Prevent the electron beam from spreading.

The waves are squeezed into a beam.

For more information, please see Radar Tutorial EU site for the article Traveling Wave Tube

See Wikipedia's article on Traveling-wave tube

For in-depth information, please see Egr MSU edu site for the pdf document Recent theory of traveling-wave tubes: a tutorial-review

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Prior to testing any RADAR system, the operator should first:

Assure no personnel are in front of the antenna.

The same device powers the radar and microwave oven--magnetron. Radar does not have the door like microwave oven, so standing in front one should never be done.

For more information, please see the CDC Gov site for the pdf document Recommendations for the Report RI 9657, Testing Radar-Based Collision Warning Systems on Heavy Equipment

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In the term “ARPA RADAR,” ARPA is the acronym for which of the following?

(A).   Automatic RADAR Plotting Aid.

The purpose of this system is to help avoid collisions by constantly updating the radar map.

Please review the Code of Federal Regulations, Title 33, Chapter I, Subchapter P, Part 164, § 164.38 Automatic radar plotting aids (ARPA). The Appendix B provides overall info. Below, listed first two paragraphs.

Appendix B to § 164.38 - U.S. Maritime Administration Collision Avoidance System Specification

A collision system designed as a supplement to both surface search navigational radars via interswitching shall be installed.

The system shall provide unattended monitoring of all radar echoes and automatic audio and visual alarm signals that will alert the watch officer of a possible threat.

The display shall be contained within a console capable of being installed adjacent to the radar displays in the wheelhouse and may form a part of the bridge console.

Provision for signal input from the ship's radars, gyro compass, and speed log, without modification to these equipments shall be made.

The collision avoidance system, whether operating normally or having failed, must not introduce any spurious signals or otherwise degrade the performance of the radars, the gyro compass or the speed log.

For well-illustrated overview of the ARPA, please see Maritimesa site for the article Automatic radar plotting aid (ARPA)

Also, please see Marine Insight article An Introduction to Radar Watchkeeping And SOLAS Requirements For Ships

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Which of the following is NOT a precaution that should be taken to ensure the magnetron is not weakened:

Keep the TR properly tuned.

WATCH OUT: This is a double-negative sentence. NOT that NOT. So, the three "wrong" answers are in fact precautions that should be taken to ensure that the magnetron is not weakened:

• Keep metal tools away from the magnet.
• Do not subject it to excessive heat.
• Do not subject it to shocks and blows.

The correct answer is NOT a precaution. The TR stands for Transmit Receive. It must be tested to assure accuracy while using high or low power. Thus, tuning has no effect on the operational integrity of the magnetron.

For more information, please see Mobility Engineering Tech site for the well-illustrated article Improving Transmit/Receive Module Test Accuracy and Throughput

Also, see Microwaves 101 site for the article Transmit/Receive Modules

And, Digikeys Electronics site for the article How to Quickly and Safely Switch an Antenna or Transducer Between Transmit and Receive Modes

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Exposure to microwave energy from RADAR or other electronics devices is limited by U.S. Health Department regulations to _______ mW/centimeter.

5.0

It is best to keep away from microwaves, as the more power leads to greater living tissue damage.

Please see the Code of Federal Regulations, Title 47 Chapter I Subchapter A Part 1 Subpart I § 1.1310 Radiofrequency radiation exposure limits., especially the Table 1 in the 47 CFR 1.1310(e)(1) Limits for Maximum Permissible Exposure (MPE)

Also see the National Archives Federal Register for article on Human Exposure to Radiofrequency Electromagnetic Fields and Reassessment of FCC Radiofrequency Exposure Limits and Policies

See the FCC page on RF Safety FAQ, which lists various issues relating to safety of radiofrequency (RF) and microwave emissions from transmitters and facilities regulated by the FCC

A great resource in this area is the MDSafeTech site Physicians for Safe Technology article on Conversion Chart, World Exposure Limits, Human Exposures EMR/EMF

An in-depth information resource from North Atlantic Treaty Organization (NATO) pdf document STO TECHNICAL REPORT TR-HFM-189, Electromagnetic Fields Exposure Limits

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RADAR collision avoidance systems utilize inputs from each of the following except your ship’s:

Anemometer.

From kb9lth:

An anemometer measures wind speed and isn't applicable to collision avoidance.

The other choices are an important source of data for the RADAR collision avoidance system, as it does use the

• Gyrocompass
• Navigation position receiver
• Speed indicator

For more information, please see Wikipedia's article on Anemometer

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