*Question T9B08:
Which of the following is a source of loss in coaxial feed line?*  

*Correct Answer is  D: All these choices are correct*  

### AI Response: (may contain errors)  

To understand why "All these choices are correct" is the right answer for the source of loss in coaxial feed line, let's break down each option:

1. **Water intrusion into coaxial connectors**:
   - Water can cause corrosion and increase resistance at the connection points, leading to signal loss. Moisture can also affect the dielectric properties of the coaxial cable, further degrading performance.

2. **High SWR (Standing Wave Ratio)**:
   - A high SWR indicates that there is a significant mismatch between the antenna and the feed line. This mismatch can cause reflected power, which does not contribute to radiating the signal and can lead to losses in the feed line. The formula for SWR is:
   $$SWR = \frac{1 + |\Gamma|}{1 - |\Gamma|}$$
   where $\Gamma$ is the reflection coefficient.

3. **Multiple connectors in the line**:
   - Each connector introduces additional resistance and potential points of failure. The more connectors in the line, the greater the cumulative loss due to reflections and resistive losses at each connection.

Since all these factors contribute to losses in a coaxial feed line, the correct answer is indeed **D: All these choices are correct**.

### Summary:
- **Correct Answer**: D (All these choices are correct)
- **Reasons**:
  - Water intrusion leads to corrosion and increased resistance.
  - High SWR causes reflected power and losses.
  - Multiple connectors add resistive losses and potential mismatches.

Understanding these sources of loss is crucial for maintaining efficient communication in amateur radio operations.