kit/si570avrusb.c has a bug. in si570avrusb_open, there is a call to setBPF. For some reason, this activates the band-pass filters (every time the device is opened).
This is seriously wrong. There are softrocks with a switchable BPF and softrocks without one (the Ensemble RXTX). When there is no switabhe BPF, the same MCU pins are used to control PTT. What happens with hamlib is that it activates PBF every time you open the device, and this effectively kills PTT.
There is no need to set the BPF on every open; this is done once from a configuration program (currently Windows only, I think).
I commented this call out and my RXTX started working. It was not working before under Linux. (For some reason, it was working with hamlib under Windows; maybe a different version of hamlib).
Thanks, Sivan Toledo, 4X6IZ