Logging in (or registering) will help the system to select questions that you need to focus on.

G3A10

What causes HF propagation conditions to vary periodically in a 28 day cycle?

Select	Answer
A	The position of the Moon in its orbit
B	Cyclic variation in the Earth's radiation belts
C	The Sun's rotation on its axis
D	Long term oscillations in the upper atmosphere

---

Hamboozler: Copyright 2007 Four Batons Technology. All rights reserved.
By continuing to use this site, you are agreeing to the Privacy Policy and Terms of Service.
Contact Us