Q: I have read in some of the model magazines that the F2 button on the DT400 is a pressure sensitive playable whistle button. I have not noticed any difference in sound with the F2 button on my DT400. Is there some way to determine if this feature is present on my throttle? A: Most Digitrax DT400 and all DT402 series throttles have the capability of implementing the playable whistle feature when used with Digitrax sound decoders.Prior to the release of Digitrax sound decoders this feature was considered as an experimental throttle feature and was not fully documented. Once Digitrax released ...