I know this is a simple question but how do you switch your frequencies in the CDU ? In the tune mode you can enter the different freqs but how do you switch between them. I notice a gauge that has the nav and com freqs but you can only type in the new freqs and doesn't seem to be able to swith to the ones in the CDU....Thx  Dennis

Must be someone out ther with an answer ?   Dennis

Maybe you can clarify the question?  All you have to do is type the frequency and press the line key to insert it, but you mentioned that (?) 

The NAVs don't have a standby, so whatever you insert is active.  For the COMs, if you insert the freq. into the top line, it should move the current frequency to the standby and the new freq you just inserted will be active.  If you insert your freq into the standby line, press the line key next to the active to flip them.

Thats what I thought but didn't seem to work..Let me try again...Thats the clue. Having standy Freq in such as atis and be able to swith back and forth...Lets try again....Dennis