*Question G2B06:
How can you avoid harmful interference on an apparently clear frequency before calling CQ on CW or phone?*  

*Correct Answer is  A: Send “QRL?” on CW, followed by your call sign; or, if using phone, ask if the frequency is in use, followed by your call sign*  

### AI Response: (may contain errors)  

To avoid harmful interference on an apparently clear frequency before calling CQ, it's important to ensure that the frequency is not already in use by other operators. Here's how each option addresses this:

1. **Correct Answer: A**  
   - **CW (Morse Code):** Send "QRL?" which is a standard inquiry meaning "Is this frequency in use?" followed by your call sign.  
   - **Phone (Voice):** Ask, "Is the frequency in use?" followed by your call sign.  
   - This method is direct and polite, allowing any operators already using the frequency to respond and inform you if the frequency is occupied.

2. **Why the other choices are incorrect:**

   - **Choice B:** Listen for 2 minutes before calling CQ.  
     - While listening is a good practice, it alone may not reveal if the frequency is in use, especially if the other operators are in a pause or using a mode you cannot hear. It lacks the proactive step of asking if the frequency is in use.

   - **Choice C:** Send the letter “V” in Morse code several times and listen for a response, or say “test” several times and listen for a response.  
     - Sending "V" or saying "test" does not clearly communicate your intention to check if the frequency is in use. It might be interpreted as a signal check rather than an inquiry about frequency usage.

   - **Choice D:** Send “QSY” on CW or announce “the frequency is in use,” then give your call sign and listen for a response.  
     - "QSY" means to change frequency, which is not appropriate when you are trying to determine if a frequency is clear. Announcing "the frequency is in use" is misleading if you are not certain it is occupied.

**Rules of Thumb:**
- Always verify if a frequency is clear before transmitting.
- Use standard procedures like "QRL?" or asking "Is the frequency in use?" to avoid causing interference.
- Listening is important, but actively asking ensures clarity and respect for other operators.