Why do I keep getting Error Message 137 - on Apollo 700 & Apollo 2 800?

A list of things to check if you get Error Message 137 on your Apollo 700 or Apollo 2 800, including: - Solarsens number check - RF Receiver check - RF Antenna check - Software check - Solar panel power check

The full instructions with images and diagrams are included in the PDF document.

Why do I keep getting Error Message 137 - on Apollo 700 & Apollo 2 800?