Here's my old
pre-amp, a 0.6dB NF model from Research Communications -- works wonderfully!
pre-amp looks exactly the same, but has a 0.4dB NF (instead of 0.6dB). I cannot tell the difference
Both are the UHF-only models, but they also have a combined VHF/UHF version with near identical specifications.
These are expensive (UK85. + UK19. for S&H), but work wonders on deep fringe signals.