Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure
I did some checking on this. QST article shows K3S MDS using preamp 2 as -145 dBm for 6m which is pretty good. Calculating MDS for a NF of 2 dB provides -146.5 dBm using a bandpass of 500-Hz (which is what Elecraft cites for MDS). The NF for 14 MHz is 8 dB (which is nominal on most new HF receivers). MDS = -139 dBm measured by ARRL for preamp 1 I use the PR6-10 on my K3 which the same as preamp 2 in the K3S (I believe). My external ARR GasFet preamp is cited 0.5 dB NF which corresponds to -155.1 dBm (with PR6-10 off) -145 dBm is quite respectable MDS on 6m. -155 dBm is eme level. 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: dubus...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure
Just because a "device" will do under 2 dB (or whatever) doesn't mean an amplifier necessarily will. Circuit losses, mismatch and bias settings will affect the circuit NF. Additionally, something like an HP noise source is made to be a good source match, both on and off. Those with lower excess noise, indicating the presence of an attenuator are better at this than higher noise sources. Nevertheless, there can be a difference. If one of these sources is used to both tune and measure an amplifier, the NF can, and probably will be, different when connected to an antenna. These differences are probably in the noise, excuse the pun, at 6 meters but can be significant at higher frequencies. Many years ago when GaAs FET were just arriving a friend designed and built a preamp for 1296 MHz. I measured the NF at 0.6 dB, but after looking at the undercertainties the number was something like (going by memory) 0.6 dB +1, -0.6, in other words, it could be perfect. This was all due to the 10:1 input SWR. With a vector network analyzer these uncertainties can be resolved, but it's not trivial. I had to chuckle after HP donated an HP8970 to the ARRL lab years ago and they reviewed an ARR preamp and listed the NF to two decimal places, presumably because that's what the instrument reported. Wes N7WS On 5/1/2017 12:15 PM, John Stengrevics wrote: That was my reaction as well, but that is what the QST review states. John WA1EAZ On May 1, 2017, at 3:02 PM, Charlie T, K3ICH <pin...@erols.com> wrote: I'll bet it’s a lot better than that. A 39¢ GG junction FET pre-amp will do under well 2dB on 6. Charlie k3ICH -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of ab2tc Sent: Monday, May 01, 2017 2:08 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure Hi, According to the ARRL review in November, 2dB! Deaf no more. AB2TC - Knut __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure
That was my reaction as well, but that is what the QST review states. John WA1EAZ > On May 1, 2017, at 3:02 PM, Charlie T, K3ICH <pin...@erols.com> wrote: > > I'll bet it’s a lot better than that. > > A 39¢ GG junction FET pre-amp will do under well 2dB on 6. > > Charlie k3ICH > > -Original Message- > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of ab2tc > Sent: Monday, May 01, 2017 2:08 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure > > Hi, > > According to the ARRL review in November, 2dB! Deaf no more. > > AB2TC - Knut > > > stengrevics wrote >> Does anyone know what the preamp 2 noise figure is on 6 meters? I >> have not been able to find it in the owner's manual or in Fred's book. >> >> Thanks, >> >> John >> WA1EAZ > > > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/K3S-Preamp-2-Six-Meter-Noise-Figure-tp7 > 630221p7630223.html > Sent from the Elecraft mailing list archive at Nabble.com. > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html Message > delivered to pin...@erols.com > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to jstengrev...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure
I'll bet its a lot better than that. A 39¢ GG junction FET pre-amp will do under well 2dB on 6. Charlie k3ICH -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of ab2tc Sent: Monday, May 01, 2017 2:08 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure Hi, According to the ARRL review in November, 2dB! Deaf no more. AB2TC - Knut stengrevics wrote > Does anyone know what the preamp 2 noise figure is on 6 meters? I > have not been able to find it in the owner's manual or in Fred's book. > > Thanks, > > John > WA1EAZ -- View this message in context: http://elecraft.365791.n2.nabble.com/K3S-Preamp-2-Six-Meter-Noise-Figure-tp7 630221p7630223.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to pin...@erols.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3S Preamp 2 Six Meter Noise Figure
Hi, According to the ARRL review in November, 2dB! Deaf no more. AB2TC - Knut stengrevics wrote > Does anyone know what the preamp 2 noise figure is on 6 meters? I have > not been able to find it in the owner's manual or in Fred's book. > > Thanks, > > John > WA1EAZ -- View this message in context: http://elecraft.365791.n2.nabble.com/K3S-Preamp-2-Six-Meter-Noise-Figure-tp7630221p7630223.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
