CRAC Class B (2025) — Questions 501–510

U0802. BD0ZZ hears an SSB call from an amateur station and wishes to contact it. However, he only caught the district number and the suffix 2MAX of the other station's call sign. The correct reply at this moment should be:

BD0ZZ听到某业余电台的SSB呼叫并希望与之联络。但是，他只听清对方呼号的分区号和后缀为2MAX。此时的正确回叫应当是：

Exam tips · 考试提示

The correct SSB reply states the partial call you heard, your own call, and politely asks for the missing prefix — concise and clear. "QRZed?" (B) means "who is calling me?", and the verbose options (C/D) are poor operating practice.

U0803. The meaning of the DX Summit message "PY2SS 28005.3 KH6/N6GQ simplex, fading signal in SA 2040 15 Feb 2012" is:

DX Summit消息“PY2SS 28005.3 KH6/N6GQ simplex, fading signal in SA 2040 15 Feb 2012”的意思是：

Exam tips · 考试提示

PY2SS is a Brazilian (PY) station; KH6 is Hawaii; "fading signal in SA" (South America) means the Brazilian reporter heard the Hawaiian station with a weak, fading signal — i.e., poorly. Guam would be KH2/KH0, not KH6.

U0804. The meaning of the DX Summit message "JA2WS 14009.6 E51WWA Calling CQ, no takers, Cook Is 0052 14 Feb 2018" is:

DX Summit消息“JA2WS 14009.6 E51WWA Calling CQ, no takers, Cook Is 0052 14 Feb 2018”的意思是：

Exam tips · 考试提示

The spot format is: reporter (JA2WS) heard station (E51WWA) doing something. "E51WWA Calling CQ, no takers, Cook Is" means the Cook Islands station E51WWA was calling CQ with no replies. JA2WS is the reporter, not the caller.

U0805. SSTV contacts on the 20 m band are most commonly found at:

20米波段的SSTV联络最常见于：

Exam tips · 考试提示

On 20 m, SSTV activity is conventionally centered around 14.230 MHz (USB). 14.260 is the IOTA/SSB area, 14.040/14.030 are CW segments, so those are not the SSTV spot.

U0806. IOTA activity on the 20 m band is most commonly found at:

20米波段的IOTA活动最常见于：

Exam tips · 考试提示

IOTA (Islands On The Air) hunters conventionally gather at 14.260 MHz for SSB and 14.040 MHz for CW on 20 m. The other SSB/CW pairings are not the standard IOTA centers.

U0807. According to contest convention, the frequencies generally NOT used for the IOTA contest are:

按照竞赛惯例，通常不用于IOTA竞赛的频率有：

Exam tips · 考试提示

IOTA contest band plans avoid the top of the 80 m CW segment 3560–3600 kHz (it is reserved/avoided by convention), while the other ranges listed are within normal IOTA operating segments. Per the question's key, 3560–3600 kHz is the non- IOTA frequency block.

U0808. Generally speaking, the best time period for 10 m band DX communication is:

通常来说，10米波段DX通信的最佳时段是：

Exam tips · 考试提示

The 10 m band (28 MHz) is primarily supported by daytime F2- layer propagation, so daytime is its best DX window. At night (B) and during very low solar flux (D) 10 m goes quiet; CME events (C) are sporadic and not the "usual" best time.

U0809. When applying for the WAS (Worked All States) award, which of the following call-sign cards cannot be used as proof of contact:

申请WAS奖状时，不能用以下哪个呼号的卡片作为通联证明：

Exam tips · 考试提示

WAS requires contacts with the 50 US states. VA3EJ is a Canadian (VE3 area) call, not a US state, so it cannot count. AC6HY (California), N8DX (Ohio), and KC1XX (Maine) are all US calls.

U0810. To apply for the 5-band WAZ award (5BWAZ), at least how many zone cards must be submitted:

申请五波段WAZ奖状（5BWAZ），至少要提交多少个分区的卡片：

Exam tips · 考试提示

The 5BWAZ award requires confirmed contacts with all CQ zones across five bands; per the official question key the minimum number of zone cards to submit is 198. Note: candidates should follow the published CQ WAZ rule for the exact threshold; the source answer key here specifies 198.

U0811. For amateur radio operators in our country, which of the following stations is the rarest and most difficult to contact:

对于我国爱好者来说，以下电台中最稀有，最不易通联的是：

Exam tips · 考试提示

KP5 is the Desecheo Island prefix — one of the most wanted and rarely activated DXCC entities, hence the hardest to work. VK0HR (Heard Island), AH0K (Northern Mariana), and ZS1EZ (South Africa) are rarer-than-average but far more frequently on the air than KP5.