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Re: DEM 13LNA Preamp



Hi Ken

I remember reading in Technical Topics in RadCom (the RSGB's comic) a tip from
G4DGU (of Mutek fame) about adjusting for minimum noise. He said that you should
find a signal on the required band, turn your radio to FM and adjust your antenna
until it is in "rough noise". Then adjust your pre-amp for the best signal. The
rationale behind this being that the FM detector is non-linear at this level and a
small improvement in the input signal would reflect to a larger degree in the
received signal. Being FM, I believe that it also meant that you would get the
best NF rather than maximum gain.

I think this tip was published around 1980, I'd love to find the reference
again. Obviously this would not give you a noise figure, but it would mean
that you could be confident of getting things as good as possible.

Jonathan
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