Antenna tuners for receive have not been very useful in my experience, nor have
preamps. The exception is trying to work full duplex on marine radios, then you
need a good preselector so that your xmtr does not totally overwhelm the rcvr
that is tuned to a nearby freq. It is easy to be fooled by preamps, they make
things louder, but they normally amplify noise as much as signal so you are not
gaining in S/N ratio. Similarly, antenna tuners give you a peak and you get
excited, but compare it to an untuned longwire and you wont hear any difference
in most cases. In the case of poorly designed rcvrs, a tuner or tuned preamp
might help make up for poor front end design, but with a good rcvr, they just
dont do much in my experience. Read a good communications electronics book
about noise floor and what it really means. You'll see that there is no magic
bullet for reducing random incoherent noise. DSP can work wonders in removing
non random noise (hetrodynes, spectral notches, etc). Digital modulation can
also work wonders in giving noise free comms. But, when all is said and done
noise is random and random stuff is hard to remove. Its all about entropy and
electrons. Directional antennas... now there is a way to improve SN, big time
in some cases.