Chris Bartram G4DGU
I have a Hermes Lite 1 (essentially much the same as the HL2, but minus much of the analogue I/O circuitry). I built mine a few years ago with the idea of using it as a microwave IF. Although with HB input filters and QUISK it gave a pretty good account of itself on HF, the conversion from the 28MHz region to the 144MHz IF of most of my transverters was the deciding factor and I didn't take the project further.
Why? If there's one thing that the design of receivers for type-approved use has taught me is to minimise the number of frequency conversions in any system. Apart from the effect on dynamic performance, Frequency conversion nearly always shows-up gotchas, and multiple conversion shows-up multiple gotchas. These will often multiply exponentially and oft-times can't be be easily designed-out. Also the acquisition of a FDM-DUO transceiver at a very reasonable price finally made the decision for me ...
I'm not suggesting that the HL1 or 2 are in any way junk. They're not! I think the concept using the CATV modem chip and the FPGA design are really neat. In the last few weeks I have been looking at my HL1 wondering what I could use it for. I have ideas, but I'm determined to finish my current projects first!