Volume 3 2A851

1. **9. (403) A very-high frequency FM radio is mainly used on aircraft that**

A. contact ground forces

B. use Air Force controlled airfields

C. contact airborne tankers for fuel

D. are under the control of civilian air traffic controllers

2. **3. (401) What is the transmitted frequency when a high-frequency radio control is set to 27.5 megahertz (MHz), the signal is modulated by a 1000-hertz tone, and lower sideband mode is selected?**

A. 26.500

B. 27.499 MHz

C. 27.501 MHz

D. 27.600 MHz

3. 59. (415) When checking the KYK–13 for stored crypto keys, the presence of a valid key is indicated by

A. one 60 Hz audible beep.

B. one red indicator flash.

C. two 60 Hz audible beeps.

D. two red indicator flashes.

4. 46. (413) The major difference between the U–92A/U and the U–94A/U jack is the

A. U–92A/U jack has a PTT button.

B. U–94A/U jack has a PTT button.

C. U–94A/U is located on the pilot’s throttle grip.

D. U–92A/U requires an additional wire for the talk switch.

5. 47. (413) When connecting the WM–85/U interphone cable to the U–94A/U, what wire color is connected to the PTT button on the U–94A/U?

A. White.

B. Green.

C. Black.

D. Yellow.

6. 42. (413) The CALL switch applies a DC voltage to the CALL control line and activates the AGC circuits in all aircraft control panel's headset amplifiers causing the CALL audio to be heard at least how many dB louder than any other signals present?

A. 2.

B. 4.

C. 6.

D. 8.

7. 18. (406) When not operating in the secure voice mode, two signals are received simultaneously on the same operating net, the Have Quick II radio automatically goes into conferencing. It does this by

A. resetting the net number for communication

B. setting the receiver to narrowband reception

C. injecting a beat frequency to prevent loss of intelligence

D. offsetting the second transmitter frequency by 25 kilohertz

8. 20. (406) The HAVE QUICK II multiple word-of-day modification provided loading capacity that allows entry of up to

A. two words-of-day for 2 day use

B. four words-of-day for 4 day use

C. six words-of-day for 6 day use

D. eight words-of-day for 8 day use

9. **15. (405) How many frequencies are available for use by the main receiver in the ARC–164 ultra-high frequency radio?**

A. 10000

B. 7000

C. 3500

D. 7

10. 56. (415) If you need to store 12 cryptographic keys, then how many KYK–13 devices will you require?

A. 1.

B. 2.

C. 4.

D. 6.

11. 28. (409) Which one of the following frequencies is not reserved for emergency use?

A. 8.0 MHz

B. 40.5 MHz

C. 121.5 MHz

D. 243.0 MHz

12. 38. (412) One purpose of the interphone system is to

A. prevent the radio transmitters from being over modulated

B. remove amplitude variations from the aircraft warning tones

C. provide a means of keying and modulating the radio transmitters

D. filter out 60-Hz hum in the audio signals going to the radio systems

13. 8. (402) In the ARC–190 high-frequency radio system, the high-frequency coupler matches the impedance of the antenna to the receiver-transmitter in order to

A. increase the voltage standing wave ratio

B. give maximum power transfer

C. increase receiver selectivity

D. increase receiver sensitivity

14. 48. (414) Which is not a level of built-in-test (BIT) on the airborne digital interphone system?

A. Power-up BIT.

B. Degraded BIT.

C. Continuous BIT.

D. Maintenance BIT.

15. **39. (412) The term used to describe the lines used to determine whether a transceiver connected to the interphone system will be in the transmit or receive condition is**

A. control lines

B. receiver audio lines

C. system ground lines

D. microphone audio lines

16. 44. (413) Which transmission operation of the interphone system is most advantageous to pilots/copilots?

A. One-button operation because it is less time consuming.

B. One-button operation because it allows pilot/copilot to talk on radios and maintain comm with crew.

C. Two-button operation because it is less time consuming.

D. Two-button operation because it allows pilot/copilot to talk on radios and maintain comm with crew.

17. 14. (404) We call the C–11029/ARC–186 a true comm/nav control box because

A. rivet work force changed its design

B. it controls both the very-high frequency AM and FM systems

C. it controls both the very-high frequency radio and the VOR/ILS receiver

D. automatic direction finding and homing share as many characteristics with the navigation systems as they do with communication systems

18. **17. (406) The Have Quick II radio's entry point in the frequency-hopping pattern is established by the word-of-day; however, it is actually programmed by**

A. time-of-day

B. the net number

C. multiple word-of-day

D. universal time coordinated

19. **19. (406) An advantage of the remote Have Quick II configuration over the panel mount configuration in an aircraft is that it**

A. is more convenient for maintenance

B. can be used with a remote channel indicator

C. reduces cost by using existing aircraft wiring

D. can be used with a ultra-high frequency direction finding system

20. **23. (407) The remote tuning panel cannot control the ARC–210 radio system if the**

A. radio set control is turned on

B. radio set control is turned off

C. remote volume control is turned on

D. remote volume control is turned off

21. 7. (402) Which version of the ARC–190 high-frequency radio system receiver-transmitter must be installed to operate properly if the system has a CU–2275(V)1 high-frequency coupler installed?

A. RT–1341(V)1.

B. RT–1341(V)2

C. RT–1341(V)3

D. Any of the above

22. 36. (411) When activated, the emergency locator transmitter continuously transmits on frequencies

A. 8.0 and 121.5 MHz

B. 243.0 and 282.8 MHz

C. 254.5 and 282.8 MHz

D. 121.5 and 243.0 MHz

23. **16. (406) The Have Quick II frequency-hopping pattern and rate is programmed by the**

A. time-of-day

B. word-of-day

C. net number used

D. universal time coordinated

24. **1. (401) The primary reason the high-frequency radio uses single sideband modulation is**

A. that fidelity is greatly increased

B. the transmitter output power is 10 watts

C. the system can use a very wide-band pass

D. that it provides many channels to operate on

25. 41. (413) The purpose of the +17 to +29 VDC on the CALL control line of the C–6567 is to

A. reduce the level of CALL audio output.

B. disable the mic amplifier during CALL operation.

C. activate the AGC circuits in the headset amplifiers.

D. energize the CALL switch on the front panel of the C–6624.

26. **31. (409) Which one of the following is not an operating mode of the PRC–90 emergency radio?**

A. Morse code

B. Two-way voice communication

C. Three-way voice communications

D. Variable audio modulation between 1000 and 300 Hz

27. **33. (409) The emergency communications system that emits pulses of high-frequency sound is the**

A. parachute radio (PR).

B. crash position indicator (CPI).

C. underwater acoustical beacon (UAB).

D. emergency locator transmitter (ELT).

28. 2. (401) The typical high-frequency radio has

A. 7,000 channels spaced 100 hertz apart

B. 7,000 channels spaced 25 kilohertz apart

C. 280,000 channels spaced 100 hertz apart

D. 280,000 channels spaced 25 kilohertz apart

29. **11. (403) Which very-high frequency radio system uses two antennas?**

A. FM homing

B. AM communications

C. FM communications

D. AM direction-finder

30. **37. (411) What switch on the emergency locator transmitter (ELT) resets the impact sensor circuits to a predetermined level after installation of the ELT?**

A. AUTO-OFF-RESET switch

B. ELT operation switch

C. g-force reset switch

D. Master switch

31. **5. (402) Which is not a mode of operation for the ARC–190 high-frequency radio system?**

A. FM

B. AME

C. USB data

D. LSB voice

32. 35. (410) Inadvertent activation of the underwater acoustical beacon from moisture is prevented by

A. a switch design

B. an aluminum alloy case

C. the aircraft mounting method

D. a predetermined resistance threshold

33. 40. (413) The C–6567/AIC–25 interphone set control

A. is a bulkhead-mounted unit

B. has a five-position rotary select switch used to key the radios

C. has eight monitor/volume controls that are switches and potentiometers

D. has a main volume control used to compensate for the weak audio of a radio system

34. 52. (414) On the airborne digital interphone system, when either the crew compartment or boom compartment is in the local ICS mode, no communication between the front and back can occur without the use of the

A. ICS function.

B. EMG function.

C. CALL function.

D. HOT MIC function.

35. **25. (408) What LRU is used to control the ARC–210 radio system in the event of a dual integrating processing failure?**

A. Radio set control

B. Control display unit

C. Remote tuning panel

D. Remote volume control

36. 29. (409) Parachute emergency radios transmit on the

A. VHF-AM emergency frequency

B. VHF-FM emergency frequency

C. UHF emergency frequency

D. HF emergency frequency

37. 32. (409) The emergency communications system that deploys from the aircraft before or at impact to give it a better chance of surviving a crash is the

A. parachute radio (PR)

B. crash position indicator (CPI)

C. underwater acoustical beacon (UAB)

D. emergency locator transmitter (ELT)

38. 34. (410) The underwater acoustical beacon can operate in fresh or salt water to a depth of

A. 15,000 feet

B. 20,000 feet

C. 25,000 feet

D. 30,000 feet

39. **26. (408) How do you swap the active and standby frequencies of the ARC–210 radio system using the remote tuning panel?**

A. Pressing the outer knob

B. Pressing the inner knob

C. Rotating the outer knob

D. Rotating the inner knob

40. 54. (414) When the airborne digital interphone system is in emergency mode, IACP #3 is directly connected to

A. HF radio #1.

B. comm radio #1.

C. comm radio #2.

D. comm radio #3.

41. 64. (416) If the CYZ–10 is placed in long-term storage in the OFF condition, then batteries are expected to last approximately

A. 30 days.

B. 79 days.

C. 119 days.

D. 156 days.

42. **6. (402) You are using a learned preset for the ARC–190 high-frequency radio system. For this application, the transmit tune time is less than**

A. 5 milliseconds

B. 25 milliseconds

C. 35 milliseconds

D. 50 microseconds

43. 43. (413) Which crewmembers will receive messages during hot-mic operation?

A. Only those with the INT switch activated.

B. All those connected to the interphone system.

C. Only those with the hot-mic talk switch activated.

D. Only those with the hot-mic listen switch activated.

44. 60. (415) Which control on the KYK–13 transfer device transfers a key into the selected storage address?

A. Address switch.

B. Mode select switch.

C. Initiate button On.

D. Initiate button Off.

45. 51. (414) The forward external interphone receptacle in the airborne digital interphone system (ADIS) system allows the operator to transmit on a radio, even though the other two external receptacles cannot, because it is connected to the

A. pilot’s interphone audio control panel (IACP).

B. pilot’s intercom control panel (ICP).

C. boom operator’s forward IACP.

D. boom operator’s forward ICP.

46. 62. (416) Which of the following is not a primary purpose of the CYZ–10 data transfer device?

A. Store COMSEC data.

B. Process host/application data.

C. Store frequency hopping data.

D. Store electronic keying material.

47. 58. (415) If the mode select switch on the KYK–13 is set to OFF CHECK and the user presses the INITIATE button, then the KYK–13 will

A. zeroize a single stored key.

B. zeroize all stored keys.

C. verify presence of a single stored key.

D. verify presence of a all stored keys.

48. 67. (417) Which one of the following units is needed to transfer crypto variables into the KY–58 processor?

A. Z–AHQ adapter.

B. KY–75 processor.

C. KYK–13 fill device.

D. KY–58 RCU control panel.

49. 61. (415) Why does the KYK–13 parity light flash on and off continuously?

A. Because battery power is low.

B. Because stored key is no longer valid.

C. Because the unit is perfoming BIT.

D. Because key transfer was prevented.

50. 13. (404) The frequency range of the ARC–186 very-high frequency radio receiver in the FM mode is from

A. 30 to 87.975 megahertz

B. 38 to 87.975 megahertz

C. 108 to 151.975 megahertz

D. 116 to 151.975 megahertz

51. 50. (414) The VOL adjustment on the ADIS interphone audio control panel allows the operator to

A. only adjust received signals individually.

B. only adjust combined received signals simultaneously.

C. adjust combined received signals simultaneously or individually.

D. adjust combined transmit and receive signals simultaneously or individually.

52. 63. (416) The CYZ–10 has a sealed case with only

A. one external opening.

B. two external openings.

C. three external openings.

D. four external openings.

53. 65. (416) What is the purpose of the data transfer device (DTD) zeroize function?

A. To activate all data content within the DTD.

B. To initiate a destructive BIT within the DTD.

C. To erase the crypto ignition key data from DTD.

D. To erase all battery backed memory in the DTD.

54. 45. (413) The C–6624/AIC–25 allows a crewmember to talk on the

A. hot-mic and CALL functions.

B. two-button and CALL functions.

C. CALL and interphone functions.

D. hot-mic and interphone functions.

55. **21. (407) What LRU provides primary control of the ARC–210 radio system?**

A. Radio set control

B. Remote tuning panel

C. Receiver/transmitter

D. Remote volume control

56. **24. (407) If the ARC–210 radio system high pass filter is inoperable, what symptom(s) may be present to the radio operator?**

A. Receiving FM commercial stations below 108 MHZ

B. Receiving FM commercial stations above 108 MHZ

C. Bleedover of aircraft’s FM transmissions below 108 MHZ

D. Bleedover of aircraft’s FM transmissions above 108 MHZ

57. 66. (417) What KY–58 line replaceable unit (LRU) has the primary function of transmitting and receiving secure voice messages?

A. Z–AHQ adapter.

B. RCU control panel.

C. KYK–13 fill device.

D. TSEC secure voice processor.

58. 53. (414) When CALL mode is activated on the airborne digital interphone system, all radios (excluding aural warnings) are

A. increased to 6dB of max volume.

B. decreased to 6dB of max volume.

C. increased to 8dB of max volume.

D. decreased to 8dB of max volume.

59. **12. (404) On which frequencies can the ARC–186 very-high frequency radio not transmit in the AM mode?**

A. 30 to 87.975 megahertz

B. 38 to 87.975 megahertz

C. 108 to 115.975 megahertz

D. 116 to 151.975 megahertz

60. **10. (403) Which very-high frequency radio system would have the best chance of receiving a signal from a station located beyond the horizon?**

A. Localizer/glideslope

B. Very-high frequency AM

C. Very-high frequency FM

D. Very-high frequency omnirange

61. 49. (414) The airborne digital interphone system (ADIS) interphone audio control panel provides monitoring facilities for listening to audio signals on how many possible channels?

A. 8.

B. 10.

C. 12.

D. 14.

62. 70. (418) The crewmembers address the secure voice system through the

A. interphone system.

B. AN/ARC 210 switch panel.

C. KY–100 mode control panel.

D. Have Quick II radio set control.

63. **22. (407) Which LRU will automatically take over in the event of a failure in the ARC–210 radio system primary control method?**

A. Radio set control

B. Control display unit

C. Remote tuning panel

D. Remote volume control

64. 27. (408) The ARC–210 radio system must be tuned within which frequency range to receive tactical/close air support information? a. 30 to 87.975 MHz. b. 108 to 117.975 MHz. c. 156 to 173.975 MHz. d. 225 to 399.975 MHz.

A. 30 to 87.975 MHz

B. 108 to 117.975 MHz

C. 156 to 173.975 MHz

D. 225 to 399.975 MHz

65. 57. (415) The capability of the KYK–13 to connect to different crypto units or another KYK–13 is provided by

A. one chasis mounted five-pin connector.

B. two chasis mounted five-pin connectors.

C. one chasis mounted six-pin connector.

D. two chasis mounted six-pin connectors.

66. 55. (414) When the airborne digital interphone system (ADIS) interphone adapter unit passes priority one input signals, the signals are passed

A. with 6dB signal increase.

B. with 6dB signal attenuation.

C. with 8dB signal attenuation.

D. without signal level adjustment.

67. 68. (418) What is the purpose of the KY–100 main terminal unit?

A. Establishes operating mode selection and code zeroing.

B. Controls plain text, cipher, and guard transmission levels.

C. Encodes and decodes transmitted and received audio signals.

D. Converts digital voice text into analog cipher text for RF transmission.

68. 30. (409) The PRC–90 hand-held emergency radio transmits on what two fixed channels?

A. 8.0 and 121.5 MHz

B. 243.0 and 282.8 MHz

C. 254.5 and 282.8 MHz

D. 121.5 and 243.0 MHz

69. **4. (401) Which is true concerning high-frequency radio reception?**

A. Antenna coupler is required to match antenna impedance

B. Audio fidelity is higher than in ultra-high frequency radios

C. The receiver sensitivity is more critical than receiver selectivity

D. The receiver must be capable of receiving unmodulated upper and lower sideband signals

70. 69. (418) Which of the following is not a function of the COMSEC mode control panel?

A. Controls delayed push-to-talk mode.

B. Controls plain text, cipher, and guard transmission levels.

C. Allows selection of command or V/UHF radio for COMSEC mode.

D. Allows selected radio audio signals to be passed through the intercom.

Volume 3 2A851

1. 9. (403) A very-high frequency FM radio is mainly used on aircraft that

2.

What first name or nickname would you like us to use?

2. 3. (401) What is the transmitted frequency when a high-frequency radio control is set to 27.5 megahertz (MHz), the signal is modulated by a 1000-hertz tone, and lower sideband mode is selected?

3. 59. (415) When checking the KYK–13 for stored crypto keys, the presence of a valid key is indicated by

4. 46. (413) The major difference between the U–92A/U and the U–94A/U jack is the

5. 47. (413) When connecting the WM–85/U interphone cable to the U–94A/U, what wire color is connected to the PTT button on the U–94A/U?

6. 42. (413) The CALL switch applies a DC voltage to the CALL control line and activates the AGC circuits in all aircraft control panel's headset amplifiers causing the CALL audio to be heard at least how many dB louder than any other signals present?

7. 18. (406) When not operating in the secure voice mode, two signals are received simultaneously on the same operating net, the Have Quick II radio automatically goes into conferencing. It does this by

8. 20. (406) The HAVE QUICK II multiple word-of-day modification provided loading capacity that allows entry of up to

9. 15. (405) How many frequencies are available for use by the main receiver in the ARC–164 ultra-high frequency radio?

10. 56. (415) If you need to store 12 cryptographic keys, then how many KYK–13 devices will you require?

11. 28. (409) Which one of the following frequencies is not reserved for emergency use?

12. 38. (412) One purpose of the interphone system is to

13. 8. (402) In the ARC–190 high-frequency radio system, the high-frequency coupler matches the impedance of the antenna to the receiver-transmitter in order to

14. 48. (414) Which is not a level of built-in-test (BIT) on the airborne digital interphone system?

15. 39. (412) The term used to describe the lines used to determine whether a transceiver connected to the interphone system will be in the transmit or receive condition is

16. 44. (413) Which transmission operation of the interphone system is most advantageous to pilots/copilots?

17. 14. (404) We call the C–11029/ARC–186 a true comm/nav control box because

18. 17. (406) The Have Quick II radio's entry point in the frequency-hopping pattern is established by the word-of-day; however, it is actually programmed by

19. 19. (406) An advantage of the remote Have Quick II configuration over the panel mount configuration in an aircraft is that it

20. 23. (407) The remote tuning panel cannot control the ARC–210 radio system if the

21. 7. (402) Which version of the ARC–190 high-frequency radio system receiver-transmitter must be installed to operate properly if the system has a CU–2275(V)1 high-frequency coupler installed?

22. 36. (411) When activated, the emergency locator transmitter continuously transmits on frequencies

23. 16. (406) The Have Quick II frequency-hopping pattern and rate is programmed by the

24. 1. (401) The primary reason the high-frequency radio uses single sideband modulation is

25. 41. (413) The purpose of the +17 to +29 VDC on the CALL control line of the C–6567 is to

26. 31. (409) Which one of the following is not an operating mode of the PRC–90 emergency radio?

27. 33. (409) The emergency communications system that emits pulses of high-frequency sound is the

28. 2. (401) The typical high-frequency radio has

29. 11. (403) Which very-high frequency radio system uses two antennas?

30. 37. (411) What switch on the emergency locator transmitter (ELT) resets the impact sensor circuits to a predetermined level after installation of the ELT?

31. 5. (402) Which is not a mode of operation for the ARC–190 high-frequency radio system?

32. 35. (410) Inadvertent activation of the underwater acoustical beacon from moisture is prevented by

33. 40. (413) The C–6567/AIC–25 interphone set control

34. 52. (414) On the airborne digital interphone system, when either the crew compartment or boom compartment is in the local ICS mode, no communication between the front and back can occur without the use of the

35. 25. (408) What LRU is used to control the ARC–210 radio system in the event of a dual integrating processing failure?

36. 29. (409) Parachute emergency radios transmit on the

37. 32. (409) The emergency communications system that deploys from the aircraft before or at impact to give it a better chance of surviving a crash is the

38. 34. (410) The underwater acoustical beacon can operate in fresh or salt water to a depth of

39. 26. (408) How do you swap the active and standby frequencies of the ARC–210 radio system using the remote tuning panel?

40. 54. (414) When the airborne digital interphone system is in emergency mode, IACP #3 is directly connected to

41. 64. (416) If the CYZ–10 is placed in long-term storage in the OFF condition, then batteries are expected to last approximately

42. 6. (402) You are using a learned preset for the ARC–190 high-frequency radio system. For this application, the transmit tune time is less than

43. 43. (413) Which crewmembers will receive messages during hot-mic operation?

44. 60. (415) Which control on the KYK–13 transfer device transfers a key into the selected storage address?

45. 51. (414) The forward external interphone receptacle in the airborne digital interphone system (ADIS) system allows the operator to transmit on a radio, even though the other two external receptacles cannot, because it is connected to the

46. 62. (416) Which of the following is not a primary purpose of the CYZ–10 data transfer device?

47. 58. (415) If the mode select switch on the KYK–13 is set to OFF CHECK and the user presses the INITIATE button, then the KYK–13 will

48. 67. (417) Which one of the following units is needed to transfer crypto variables into the KY–58 processor?

49. 61. (415) Why does the KYK–13 parity light flash on and off continuously?

50. 13. (404) The frequency range of the ARC–186 very-high frequency radio receiver in the FM mode is from

51. 50. (414) The VOL adjustment on the ADIS interphone audio control panel allows the operator to

52. 63. (416) The CYZ–10 has a sealed case with only

53. 65. (416) What is the purpose of the data transfer device (DTD) zeroize function?

54. 45. (413) The C–6624/AIC–25 allows a crewmember to talk on the

55. 21. (407) What LRU provides primary control of the ARC–210 radio system?

56. 24. (407) If the ARC–210 radio system high pass filter is inoperable, what symptom(s) may be present to the radio operator?

57. 66. (417) What KY–58 line replaceable unit (LRU) has the primary function of transmitting and receiving secure voice messages?

58. 53. (414) When CALL mode is activated on the airborne digital interphone system, all radios (excluding aural warnings) are

59. 12. (404) On which frequencies can the ARC–186 very-high frequency radio not transmit in the AM mode?

60. 10. (403) Which very-high frequency radio system would have the best chance of receiving a signal from a station located beyond the horizon?

61. 49. (414) The airborne digital interphone system (ADIS) interphone audio control panel provides monitoring facilities for listening to audio signals on how many possible channels?

62. 70. (418) The crewmembers address the secure voice system through the

63. 22. (407) Which LRU will automatically take over in the event of a failure in the ARC–210 radio system primary control method?

64. 27. (408) The ARC–210 radio system must be tuned within which frequency range to receive tactical/close air support information? a. 30 to 87.975 MHz. b. 108 to 117.975 MHz. c. 156 to 173.975 MHz. d. 225 to 399.975 MHz.

65. 57. (415) The capability of the KYK–13 to connect to different crypto units or another KYK–13 is provided by

66. 55. (414) When the airborne digital interphone system (ADIS) interphone adapter unit passes priority one input signals, the signals are passed

67. 68. (418) What is the purpose of the KY–100 main terminal unit?

68. 30. (409) The PRC–90 hand-held emergency radio transmits on what two fixed channels?

69. 4. (401) Which is true concerning high-frequency radio reception?

70. 69. (418) Which of the following is not a function of the COMSEC mode control panel?

1. **9. (403) A very-high frequency FM radio is mainly used on aircraft that**

2. **3. (401) What is the transmitted frequency when a high-frequency radio control is set to 27.5 megahertz (MHz), the signal is modulated by a 1000-hertz tone, and lower sideband mode is selected?**

9. **15. (405) How many frequencies are available for use by the main receiver in the ARC–164 ultra-high frequency radio?**

15. **39. (412) The term used to describe the lines used to determine whether a transceiver connected to the interphone system will be in the transmit or receive condition is**

18. **17. (406) The Have Quick II radio's entry point in the frequency-hopping pattern is established by the word-of-day; however, it is actually programmed by**

19. **19. (406) An advantage of the remote Have Quick II configuration over the panel mount configuration in an aircraft is that it**

20. **23. (407) The remote tuning panel cannot control the ARC–210 radio system if the**

23. **16. (406) The Have Quick II frequency-hopping pattern and rate is programmed by the**

24. **1. (401) The primary reason the high-frequency radio uses single sideband modulation is**

26. **31. (409) Which one of the following is not an operating mode of the PRC–90 emergency radio?**

27. **33. (409) The emergency communications system that emits pulses of high-frequency sound is the**

29. **11. (403) Which very-high frequency radio system uses two antennas?**

30. **37. (411) What switch on the emergency locator transmitter (ELT) resets the impact sensor circuits to a predetermined level after installation of the ELT?**

31. **5. (402) Which is not a mode of operation for the ARC–190 high-frequency radio system?**

35. **25. (408) What LRU is used to control the ARC–210 radio system in the event of a dual integrating processing failure?**

39. **26. (408) How do you swap the active and standby frequencies of the ARC–210 radio system using the remote tuning panel?**

42. **6. (402) You are using a learned preset for the ARC–190 high-frequency radio system. For this application, the transmit tune time is less than**

55. **21. (407) What LRU provides primary control of the ARC–210 radio system?**

56. **24. (407) If the ARC–210 radio system high pass filter is inoperable, what symptom(s) may be present to the radio operator?**

59. **12. (404) On which frequencies can the ARC–186 very-high frequency radio not transmit in the AM mode?**

60. **10. (403) Which very-high frequency radio system would have the best chance of receiving a signal from a station located beyond the horizon?**

63. **22. (407) Which LRU will automatically take over in the event of a failure in the ARC–210 radio system primary control method?**

69. **4. (401) Which is true concerning high-frequency radio reception?**