I recently heard that the DX Doubler (DXD) SO2R Controller by TopTen Devices, has been discontinued. Looking at their Web Site, it has completely vanished, along with the Radio-specific cables, User Manuals, etc. This controller was a great addition to my shack a few years ago. It is a very simple design, with no Microprocessors involved, and is not only useful for SO2R use, but also a fine centerpiece in a two-radio shack for everyday operation. Given its Parallel Port interface, it is understandable that the DXD box could not be expected to compete with more modern USB-based SO2R controllers. Unfortunately, these newer designs appear to be much more complex and fairly expensive. I will continue to use the DXD boxes in my station for now, but will start looking at an eventual replacement.
As you may know, I have designed a USB interface for the DXD and will wrap-up that activity in the near future. I plan to go ahead with the final version of the PC Board layout for the DXDUSB, as the project has been a great learning tool, and I would hate to leave the project unfinished. The resulting board is really a general-purpose Arduino-based decoder for the Open Two Radio Switching Protocol that is supported by SO2R controllers. I hope to be able to use it in some other Contest-station supporting roles in the future. It may be useful as a Band decoder for some radios, or for interfacing of older radios with modern Contesting software such as N1MM+.
It does seem unfortunate that all signs of support for the DXD seem to have disappeared, considering that it was still being sold just a couple months ago, but I will be looking forward to future product offerings from the folks at TopTen.