@Bob - I fully agree. They had to guarantee the full coverage 0.5-32 MHz on 100% of production, while I do the test in few points… too easy for me! 😀
> Il giorno 4 ott 2024, alle ore 18:53, Jim Whartenby via R-390 > <r-390@mailman.qth.net> ha scritto: > > Bob > But we do know what the interface is between the signal generator and antenna > input. On document page 20, the balanced RF input is in series with a 125 > ohm non-inductive resistor and the unbalanced RF input is in series with a 50 > pF capacitor. Both interfaces do not include the generator's output > impedance. > > As for the sensitivity not being what the R-390/URR or the R-390A/URR is > capable of, well there are perhaps 100's of tests that the receiver must > successfully pass before it is accepted. Tightening any of the specs to > exactly what the receiver may be capable of passing will guarantee that no > one receiver will ever pass all of the acceptance tests. Then there is the > added problem of your test equipment's error tolerance and being traceable > back to the NIST standards. Is your 10 microvolts from the signal generator > really 10 microvolts? > > Unless otherwise stated, the specification calls out a value that the > receiver must do better than. A sensitivity of just under 6.5 microvolts for > a 10 dB S+N/N with an audio power output of 10 milliwatts seems reasonable > over the range of 2 to 32 MHz for either balanced or unbalanced RF inputs. > This is perhaps typical for just about all HF receivers built for the > military, at least for what I am aware of, but I am sure that there will be > the rare exception. > > Regards, > Jim > Logic: Method used to arrive at the wrong conclusion, with confidence. > Murphy > > On Friday, October 4, 2024 at 09:39:26 AM CDT, Bob Camp <kb...@n1k.org> > wrote: > > Hi > > The gotcah here is that we really don’t know what the interface between the > signal generator and radio looked like for these official tests. Despite the > document going into a lot of detail, they did not include a schematic or a > part number. (or at least not one that I could find). There are a *lot* of > ways they might have been doing things ….. > > Bob > >> On Oct 4, 2024, at 10:19 AM, Ing. Giovanni Becattini via R-390 >> <r-390@mailman.qth.net> wrote: >> >> But when we perform the classical sensitivity test with a modulated signal, >> do we get the AM or CW value? >> >> Following the instructions I got a value of -104 dBm, i.e. 1.41 uV. Because >> I used the DA-121, the real value should be even better, far from 5 uV. And >> surely my R-390A is not as good as it could be . >> >> Is my reasoning correct? >> >>> Il giorno 4 ott 2024, alle ore 16:13, Barry <n4...@knology.net> ha scritto: >>> >>> I don’t think of 1uV as “bad” but most of these radios will beat that. >>> >>> Thanks, >>> Barry >>> >>>> On Oct 4, 2024, at 8:55 AM, Ing. Giovanni Becattini via R-390 >>>> <r-390@mailman.qth.net> wrote: >>>> >>>> Wow, thanks! >>>> >>>> By the way, do you know why the sensitivity values were so bad? Are we the >>>> ones who are taking measures that are too lenient or are they the ones who >>>> were too conservative? >>>> >>>> Thanks again >>>> >>>> Gianni >>>> >>>>> Il giorno 4 ott 2024, alle ore 15:37, Larry Haney <larry41...@gmail.com> >>>>> ha scritto: >>>>> >>>>> Hi Gianni and Barry, Tom Marcotte and Al Tirevold (SK) obtained and >>>>> cleaned up the specs for the 390A and put it on our website. Here's the >>>>> link: mil-r-13947b– (r-390a.net) >>>>> <https://www.r-390a.net/mil-r-13947b.pdf>. Unfortunately, the entry in >>>>> References page indicates it is for the R390(), but it is also the the >>>>> 390A. I will be changing that shortly. >>>>> >>>>> Regards, Larry >>>>> >>>>>> On Fri, Oct 4, 2024 at 4:49 AM Ing. Giovanni Becattini via R-390 >>>>>> <r-390@mailman.qth.net <mailto:r-390@mailman.qth.net>> wrote: >>>>>> Have ever been released official specs for the 390A? >>>>>> >>>>>> The manuals report few data and neither too correct, for what I can >>>>>> understand (e.g., sensitivity) >>>>>> >>>>>> Thanks >>>>>> ______________________________________________________________ >>>>>> R-390 mailing list >>>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 >>>>>> Help: http://mailman.qth.net/mmfaq.htm >>>>>> Post: mailto:R-390@mailman.qth.net <mailto:R-390@mailman.qth.net> >>>>>> >>>>>> This list hosted by: http://www.qsl.net <http://www.qsl.net/> >>>>>> Please help support this email list: http://www.qsl.net/donate.html >>>> >>>> ______________________________________________________________ >>>> R-390 mailing list >>>> Home: http://mailman.qth.net/mailman/listinfo/r-390 >>>> Help: http://mailman.qth.net/mmfaq.htm >>>> Post: mailto:R-390@mailman.qth.net >>>> >>>> This list hosted by: http://www.qsl.net >>>> Please help support this email list: http://www.qsl.net/donate.html >>> >> >> ______________________________________________________________ >> R-390 mailing list >> Home: http://mailman.qth.net/mailman/listinfo/r-390 >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:R-390@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ > R-390 mailing list > Home: http://mailman.qth.net/mailman/listinfo/r-390 > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:R-390@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ > R-390 mailing list > Home: http://mailman.qth.net/mailman/listinfo/r-390 > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:R-390@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:R-390@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
