Probably not, all mixers are tested in the factory prior to shipment. Conversion loss ripple can come from several places. First, make sure that your test setup is calibrated properly. For advice on how best to test your mixer, see blog posts on conversion loss ripple, isolations, spurs, and intermodulation distortion (IP3). Conversion loss ripple is also witnessed when the mixer port is reactively terminated with a reflective filter (see the previous question on VSWR). The time-tested solution to cure ripple caused by reactive terminations is to place wideband 50 W attenuators at the mixer ports to prevent fading due to the reflection of outgoing signals. We recommend at least 3 to 6 dB at the RF and IF ports for most applications.