UHF Channel Cheat Sheet

[the evil twin]

But it doesn't tell you that some 40 channel model channels don't work on the 80 channel models.
Like channel 22.

That isn't just to do solely with 80's either.
There are quite a number of 40 sets that won't tx on 22 either

Transmission on Channel 22 on later model 40's and most 80's built by the better manuf's released into Oz is inhibited as a factory setting as it is an illegal freq for voice on the ACMA freq spectrum.