*Question G2A04:
Which mode is most commonly used for voice communications on the 17- and 12-meter bands?*  

*Correct Answer is  A: Upper sideband*  

### AI Response: (may contain errors)  

In amateur radio, different bands have standard conventions for which sideband to use for voice communications. These conventions help ensure consistency and compatibility among operators.

1. **Correct Answer: Upper sideband (A)**  
   - On the 17- and 12-meter bands, the convention is to use Upper Sideband (USB) for voice communications. This is a standard practice for all amateur bands above 9 MHz, including the 17-meter (18 MHz) and 12-meter (24 MHz) bands.

2. **Why the Other Choices are Incorrect:**
   - **Lower sideband (B):** Lower Sideband (LSB) is typically used for voice communications on bands below 9 MHz, such as the 160, 80, and 40-meter bands. It is not the standard for the 17- and 12-meter bands.
   - **Suppressed sideband (C):** This term is not commonly used to describe a mode of operation. It refers to a technical aspect of single sideband (SSB) transmission where one sideband is suppressed, but it does not specify which sideband is used.
   - **Double sideband (D):** Double Sideband (DSB) transmits both sidebands and is not typically used for amateur voice communications due to its inefficiency compared to SSB, which uses only one sideband.

3. **Useful Rule of Thumb:**
   - For amateur radio voice communications:
     - Use LSB for bands below 9 MHz (e.g., 160, 80, 40 meters).
     - Use USB for bands above 9 MHz (e.g., 20, 17, 15, 12, 10 meters).

Understanding these conventions helps ensure proper operation and communication on the amateur bands.