I've been staring at the data sheets for MESFET mixers (example: Mini circuits
HJK-372H+) for a while. They have excellent compression characteristics (+14 dBm P1dB), decent LO to RF isolation (> 45 dB at my frequency of interest) and the noise figure should equal the conversion loss (7.7 dB) since it's a passive device. All of these, particularly compression, look better than pretty much all of MCL's range of diode mixers, so there must be some reason diode mixers are still being sold. In other words, where's the catch? It can't be the high LO drive, a representative Level 17 diode mixer (SYM-30DHW+) is worse than the MESFET device in every metric, with the exception of LO port VSWR. What am I missing?