NOTE: I have had reports that this modification does not work, or has been made up, please let me know if you have done it and been able to get it to work, or if you haven't !

I have had a confirmation from one person that this mod worked for him, see below for his comments:

The Cherokee AH-100 mod definately works. I bought one, did the mod exactly as described (although I had dificulty finding the solder islands at first, but once I did, it was obvious that they were put there so the mod could be done, and done very easily). It was the first mod I ever tried and it worked perfectly; ten bands of 40 channels, each with am, usb and lsb. If the radio was ever turned on before the mod was performed, you do have to short out the terminals on the radio, turn the radio to the on position, and leave it that way for 24 hours, to reset the processor.
Hope this helps!

Remove the back cover.

Find the small PCB that has the PTT and UP/DOWN switches on it.

On the reverse of this PCB you will find a group of three solder islands that end on the outside edge of the board.

Solder a bridge across all three islands.

Re-assemble the radio.

Now you will need to reset the microprocessor, this is done by removing the battery, turning on the radio and then shorting out the terminals for around 24 Hrs.

Once the microprocessor has been reset you can continue.

Make sure that the power switch is on, hold down the CH9 button and slide in the battery, you should now be able to hear the receiver, release the CH9 button and the display should appear.

Use the CH9 button to select 10 bands of 40 channels.

Now every time that you turn on the radio with the CH9 button pressed you will have 400 channels.

If you dont hold down the CH9 button when you power the radio you will have the standard channels.