*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)  

The most common frequency shift for RTTY (Radio Teletype) emissions in the amateur HF bands is 170 Hz. Here's a breakdown of why this is the correct answer and why the other options are not.

### Explanation of the Correct Answer (170 Hz)
- RTTY is a type of digital communication that uses frequency shift keying (FSK) to transmit data.
- The standard frequency shift for RTTY in amateur radio is typically set at 170 Hz. This shift allows for effective communication while minimizing interference with other signals.

### Why the Other Choices are Incorrect
- **85 Hz**: This frequency shift is too small for RTTY operations. It may not provide sufficient separation between the mark and space frequencies, leading to potential confusion in decoding.
  
- **425 Hz**: This shift is larger than the standard and could lead to increased bandwidth usage, which is not efficient for typical RTTY operations. It may also cause interference with adjacent channels.

- **850 Hz**: This is an even larger shift and is not commonly used in amateur RTTY. Such a large shift would occupy more bandwidth and is generally unnecessary for effective communication.

### Summary
- The standard frequency shift for RTTY is 170 Hz, which balances effective communication and bandwidth efficiency.
- Other shifts like 85 Hz, 425 Hz, and 850 Hz are either too small or too large for typical RTTY operations in amateur radio.

This understanding of frequency shifts is crucial for operating RTTY effectively and ensuring clear communication on the amateur HF bands.