CRAC Class B (2025) — Questions 241–250
U0239. After an amateur station establishes communication, the necessary information the two sides should exchange first is:
业余电台建立通信后，双方应首先交换的必要信息是：
Exam tips · 考试提示
Once a contact is established, the first mandatory exchange is the signal report (信号报告, typically RST). Names, QTH, and equipment details may follow, but the signal report comes first as the essential on-air information.
U0240. Why do amateur stations always exchange signal reports immediately after establishing communication?
为什么业余电台建立通信后总是立即交换信号报告？
Exam tips · 考试提示
The signal report tells both operators about current propagation and received quality, so they can choose the best mode, power, and antenna. Option A is the correct rationale. B rationalizes without reason; C (calibrating power) and D (abandoning weak contacts) are incorrect.
U0241. In modern amateur radio communication, signal reports all use the "RST format". In the abbreviation RST, the letter R stands for:
在现代业余无线电通信中，信号报告均采用“RST格式”。缩 语RST中的字母R代表：
Exam tips · 考试提示
RST = Readability (R), Strength (S), Tone (T). R stands for 可辩 度 (readability) — how easily the signal can be copied. S is strength and T is tone. Option A is correct; QRK is a separate Q- code for readability of signals.
U0242. Xiaoming and Xiaoqiang make a CW and an FM contact; both receivers indicate a signal strength of "5". For the CW contact, both rate copying as smooth, with no tone distortion or other signal defects; for the FM voice contact, both find the audio easily intelligible, without obvious distortion affecting copy. In this situation, the signal reports they should give for the CW and FM contacts are:
小明和小强进行CW和FM联络，双方的收信机均指示信号强度 为“5”。通报时，双方评价听抄顺畅，没有变调等信号缺陷； 通话时，双方认为声音易于辩识，没有明显影响听抄的失真。 此时，双方应当为CW和FM通联给出信号报告：
Exam tips · 考试提示
For CW, the RST report uses Readability-Strength-Tone: R=5 (perfectly readable), S=5 (per the S-meter), T=9 (no tone defect) → 559. For FM voice there is no tone figure, so an RS report of R=5, S=5 → 55. Option A gives the correct pair (CW 559, FM 55). The reversed pair (B) and the "always 599/59" choices (C/D) are wrong.
U0243. An amateur station should listen before transmitting (monitor first). But sometimes, because you cannot hear one side of an ongoing contact, you may mistake the frequency for being clear, and a "CQ" could then interfere with others. To minimize this, you can:
业余电台在发起呼叫前应先守听。但是，我们有时会因听不到 通信中的某一方而误认为频率空闲。此时呼叫“CQ”有可能干 扰他人联络。为尽量避免这种情况，我们可以：
Exam tips · 考试提示
Good practice (守听 first, then a "is this frequency in use?" query) avoids interrupting an in-progress contact you cannot fully hear. Option A is correct. B uses a non-standard phrase; C/D transmit first and only yield later, which can cause harmful interference and violates listen-before-transmit etiquette.
U0244. BH1ZZZ wishes to join an ongoing contact between two other stations. The correct method is:
BH1ZZZ希望加入两个电台相互之间的联络。正确的方法是：
Exam tips · 考试提示
To break into an existing QSO politely, you wait for a pause, send a brief "break", identify, and wait for an invitation. Option A is the proper procedure. B interrupts mid-transmission; C (power up and repeat) is rude and potentially interfering; D ignores etiquette even among friends.
U0245. If during a contact you hear a station in distress requesting to break in, what should you do?
如果在联络中听到有个遇险的电台要求插入，你该怎么做？
Exam tips · 考试提示
A distress (遇险) station requesting break-in has absolute priority. The correct first action is to make contact with it immediately and ascertain its needs (A). While B (routing to emergency comms volunteers) is also good practice, the answer key marks A as the direct, correct response; C/D (leave the frequency or stop transmitting) would abandon the distressed station.
U0246. When requesting to break into a conversation between two stations, a worthwhile rule of thumb is:
在请求插入两个电台间的对话之时，一个值得借鉴的经验是：
Exam tips · 考试提示
Courtesy when breaking in means considering whether your entry would disrupt the original pair's exchange (A). The other options focus on signal quality, license class, or "more interesting content" — none are the proper etiquette criterion.
U0247. If you find that an amateur station's transmitting operating technique is not quite standard, but it is not yet causing serious interference or impact, the correct action is:
若发现有业余电台的发射操作技巧不够规范，但还不至于造成 严重的干扰和影响，正确的做法是：
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For a minor, non-harmful operating lapse, the constructive approach is friendly off-air advice (phone/email) rather than public confrontation or formal complaints. Option A is correct; B (on-air scolding), C (immediate authority report), and D (association "policing") are disproportionate.
U0248. An amateur station's communication suffers serious interference from an illegal or unidentified station. The correct action is:
业余电台通信受到违法电台或者不明电台的严重干扰。正确的 做法是：
Exam tips · 考试提示
When seriously interfered with by an illegal/unknown station, the proper response is to gather evidence (time, frequency, recording) and report to the radio management authority; do not engage or retaliate. Option A is correct. B (on-air arguing) and D (jamming with high power) are themselves violations; C is partially right but A's "collect info first, then report" is the marked answer.