I have a couple Symmetricom TimeSource 3500 systems that I would like to test. Unfortunately, it requires an external GPS downconverter, either a) 090-72010-71 integrated antenna/downconverter (or 990-72050-96 kit) or b) Window/wall antenna and separate downconverter 090-72050-71 or -72. Does anyone know where to locate the 090-72010-71 antenna for a reasonable price? I see that there are a couple of window/wall downconverters on Ebay for too-high prices so that is not attractive. Although, I am wondering whether one of the window/wall downcoverters could be attached to a modern antenna/LNA. Anyone know about that? Thanks! Jim