I'm designing an IF filter for a receiver that's placed at the output of a
passive (diode-type) mixer. While the mixer's RF input is being fed with a
(nominally) 50ohm source, is it correct to think that "looking" back into the
IF port the filter is going to "see" a 50ohm impedance as well? (Normally I'd
have a buffer stage right after the mixer to re-establish impedance levels,
but in this case I'm trying to keep things low-power and hence directly feed
the mixer's output into the filter.)

Thanks,
---Joel