Hello.
There are 2 tables (5 and 6) in the datasheet of mixer LTC5576 on the page 19. Unfortunately I cannot find "input RF level" under measurement conditions as it is noticed for other mixers (e.g. LTC5577 tables 6a, 6b in the datasheet) standardly…
The LTC5576 active mixer can be a good choice for your frequencies:
https://www.analog.com/en/products/ltc5576.html#product-overview
Although it is labeled as an upconverting mixer, it can be used in downconverting applications as well. The LTC5576 datasheet…