Posted by
Conrad PA5Y on
Jul 03, 2020; 7:21am
URL: http://elecraft.85.s1.nabble.com/K3s-noise-figure-spec-tp7662748p7662839.html
Hello Charlie.
I think if you live in an area where there is high populations of amateurs such as FN20 or NW Europe it does help enormously if you can hear the DX early in the opening before the pileup really gets going. However for most urban or semi urban operators 6m is a noisy band. You only need enough gain to raise your noise floor by 10-15dB when a resonant antenna is connected. Any more than that and you have too much gain and you will be hit very hard by the HUGE signals that are around during a typical 6m opening.
This is especially important now that we are all on 50.313/50.323.
I must admit that I use an external preamp with my K3S so that I can use a band pass filter and a 2 way splitter (SDR for 50.323). I have 25dB gain and a 0.5dB NF LNA, the whole chain is- 0.5dB for the coax cable,- 1dB for the band pass filter, - 3dB for the splitter and a 6dB attenuator which I take out when on EME. My system noise figure is 2.9 dB for terrestrial and 1.6dB for EME. This is probably better than needed. The background noise on 6m dominates sensitivity. More gain than you need is counterproductive.
73
Conrad PA5Y
________________________________
From:
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Sent: 01 July 2020 17:26
To:
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Subject: Re: [Elecraft] K3s noise figure spec
I can't speak for E.M.E operations, but from over 60 years of experience on
6M, I can tell you that super sensitive receiver performance is NOT a
pre-requisite to working LOTS of DX of 50 MHz.
When the band is open, either via E or F2 propagation, signals are usually
very "loud".
The only "weak" signals are those at the initial start and end of the
opening.
I remember working a station in Alaska from here in Virginia on SSB, who was
running 10 watts to a balcony mounted Saturn-6 halo, barely 10 feet off the
ground !
He was +10 dB over S nine for over an hour.
SO, don't fret over whether your noise figure is 0.5 dB or 2.5 dB, any
decent modern radio will hear just fine.
73, Charlie k3ICH
>160 countries confirmed on 6M on SSB & CW ONLY, no PSK-31, FT-8' etc.
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