I have contacted Vertex on this problem, but so far they haven't been much help. I have two VX-351 UHF units with 16 total channels. The customer only wants to scan three channels. When a function button is set to scan, the channels that are not in the scan list can't talk to each other. For example if channel five is not in the scan list (it's a simplex channel) and both radios have the button engaged for scan, channel five on the radio will not talk to channel five on the other radio and vice versa. The only way I've been able to get this to work is to program a button for follow me scan and not use a button for scan. Doing this allows the user to use the radio as a radio and transmit and receive on whatever channel they are on with the follow me scan button engaged, as well as be able to receive channels that are in the scan list. The problem is that when a channel in the scan list is being received by a radio on a channel not in the scan list there is an audible "chop" on the receiving radio. It seems as though the dual watch timer affects this. By changing the settings on the dual watch timer, the "chop" changes according the setting (from one to five seconds). Does any one know how to get rid of the "chop" or another setting to be able to scan and use all the channels as they are intended? I know this may be confusing, but I'd appreciate any help. Thanks.