*Question G2E06:
What is the most common frequency shift for RTTY emissions in the amateur HF bands?*  

*Correct Answer is  B: 170 Hz*  

### AI Response: (may contain errors)  

In the context of amateur radio, RTTY (Radio Teletype) is a mode of digital communication that uses frequency shift keying (FSK) to transmit data. The frequency shift refers to the difference between the two frequencies used to represent the binary states (mark and space) in the transmission.

1. **Correct Answer: 170 Hz**  
   - The most common frequency shift for RTTY emissions in the amateur HF bands is 170 Hz. This shift is widely used because it provides a good balance between bandwidth efficiency and reliable communication under varying conditions. It is the standard shift for amateur RTTY operations.

2. **Why the Other Choices are Incorrect:**
   - **85 Hz:** This is a narrower shift that is not commonly used in amateur HF RTTY. It might be used in some specialized or experimental setups but is not the standard.
   - **425 Hz:** This is a wider shift than the standard 170 Hz and is not typically used in amateur HF RTTY. Wider shifts can occupy more bandwidth, which is generally undesirable in crowded HF bands.
   - **850 Hz:** This is an even wider shift and is not used for standard RTTY operations in the amateur HF bands. Such a wide shift would unnecessarily use up more bandwidth and is not practical for typical amateur use.

In summary, the 170 Hz shift is the standard for RTTY in amateur HF bands due to its efficiency and effectiveness in typical operating conditions.