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I have the same transverter here although it's in a bit of a sorry state at the moment. An article in the old ARRL UHF/Microwave Projects book by WA5VJB mentions a difficulty in getting enough clean LO power from the XLO-1 which I found to be the case with mine so I added a MMIC amplifier and pipecap filter, I don't know if mine is temp compensated or not but I added a DB6NT crystal heater and a small amount of varicap tuning and the oscillator always comes up very close to frequency and is never more than a few kHz off. I also added a preamp and pipecap filter to the RF input but that currently needs fixing. One actual fault I found when I first got it was that the Tx output was very occasionally intermittent, this turned out to be just a bad solder joint of the voltage regulator tab to the case. Sorry can't help with phase noise.