Topband: Re: Noise floor

[artinian]

I am sorry for a late reply but I was in Tuscany for a week.  Met Carlo, I5JVA
www.antenna.it and saw monstrous quads superbly mechanically designed.

> > I am still waiting for the measurements of 160m night signal and noise
> > levels in GA?
> >
> > 73 de Mario, S56A, N1YU
>
> I'm not sure I understand why you want that measurement, but I
> certainly have no interest in it.

Really no need as there is plenty of data available.  Quiet site has about 5 uV
of noise at 50 Ohms at 2 MHz in 3 kHz bandwidth with poor RX antenna.  Noise
factor Fant is above 45 dB which enables a lot of antenna inefficiency
considering 10 dB Frx.  More info is written in DL and G books which might be
unknown to USA hams.

> A person should never measure minimum noise floor required at
> night during August (when QRN is very high) in the SE USA.

Figures are probably Fant > 80dB with atmospheric noise above high man-made one.

> Noise floor requirements should always be determined with the
> narrowest selectivity under the most quiet conditions that could
> ever occur at that site during times of expected operation.

Professionals take the highest QSO probabilities and they would discount above
extreme condx.  One should miss few very weak signals in order to survive
increasing QRM and achieve best overall RX results.  However, TS-850 offers NF 
5 dB while FT-1000D is claimed to lack 70 MHz IF gain...

73 de Mario, S56A, N1YU.




>


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