Airtronics Infinity 660
I have noticed that with the pack in the Tx, the batteries in my Infinity 660 seem to run down faster than my other radio. I have always assumed that the main pack may have some draw on it even with the Tx switched off (memory back-up?). Testing the pack with it removed from the Tx is a good suggestion. It may also be worth checking if the memory is lost with the main pack removed. If it is, it may be that the main pack will backup the memory if the lithium cell is low and needs replacement.