I'm waiting for delivery on a new NX-1300DUK5 radio with display and standard keypad. This particular model has the ability to be front panel programmed without any hardware modifications or license key loads.
One of the option license keys for it enables the 40 bit ARC4 encryption feature. It's a "cheap" license, around $30 more or less. I know it's weak encryption, and has been broken. If a number of radios use it them I might spend the money and upgrade it just to experiment with it. The one nice feature is no key-loader is required, for example AES and DES.
My question here what radios currently use this encryption standard?
NX-1300DUK5.pdf