Priority Channel in Yaesu radios.... and others... can cause unexpected behavior in the radio.

The problem is generally described as: 
  • "The radio won't stay on the channel I set it to." or 
  • "The radio keeps changing frequency when I haven't touched anything." or 
  • "The channel I'm listening to keeps getting interrupted or I lose the signal and the conversation is "choppy"."
All of these are a sign that you have engaged use of the Priority Channel.  This is a great feature if you want to talk to other friends on one repeater while listening for someone on another repeater (or simplex in both cases).  The radio will listen for an incoming signal on the priority channel and change to that channel when it hears a signal.  When "listening", the radio changes to that other frequency for a matter of seconds every so often (On some models the time between lookbacks and the length of time that the radio listens to the priority channel can be set.  On others, these timers are preset at the factory and cannot be changed.  Check the options for your radio.) 

If the radio is changing channels unexpectedly, your present conversation will be interrupted when you don't expect this interruption. 

This feature has two parts to its setup.  
  • First, select the priority channel.  Select a memory channel.  Click Edit from the menu at the top. Click Set Priority Channel.  A "P" will appear along with the channel number to the left to let you know this channel is your priority channel. 
  • Second, turn the option on in Settings | Radio Menu Settings.  Check Priority Revert.  
Now:  There will ALWAYS be an assigned Priority channel. But being assigned is a moot point unless the option is turned on.  in other words, you cannot turn off the Priority channel selection; but you can control its use by the radio through the Priority Revert option