Hi Jacques, Shorting both antenna jacks eliminates most of the noise; however, there's still a small noise increase when switching from the 1-2 MC band to the 0-1 MC band. I even tried putting the top cover back in place to help eliminate stray noise from getting in through the top but I couldn't notice any difference with it on as opposed with it off.
The 6-7 MC band has the same noise level as the other bands. I think you were probably looking at the common crystal for that, right? Given this, perhaps there just a high level of atmospheric or other noise at my location. I experimented a bit with my Grundig Satellit 800 and, while the two receivers aren't nearly in the same class, I don't notice that much difference in, say 600kHz and 1200kHz so still not sure if it's atmospheric. Thanks, Barry - N4BUQ > Hi Barry, > Does it behave the same (higher noise on 0-1 MHz band) when the antenna > input is shorted ? > Just try to understand if it is internal to the receiver or just dependant > on the antenna conditions. > And.. is it also noisy on the 6-7 MHz band ? > > 73, Jacques, VE2JFE in Montreal > > -----Message d'origine----- > De : [email protected] <[email protected]> De la > part de Barry Scott > Envoyé : 21 octobre 2024 22:26 > À : R-390 Mailing List <[email protected]> > Objet : [R-390] High Noise Floor in 0-1 MC Band > > For the past few months, I've been trying to determine why the noise floor > on the 0-1 MC band in my R390/URR is so high. If I tune to a strong > station, the noise disappears so, perhaps, "noise floor" might be the wrong > term for it but in places where there's little-to-no signals, the noise is > very noticeable and all but drowns out the weak signals. > > If I switch from 0-1 MC to 1-2 MC (or virtually any other band), the noise > is reduced significantly. The difference can be on the order of > 15-20 dB on the carrier level meter. > > I presume this isn't normal but maybe it is. I think someone mentioned that > the noise on the bands under 8 MC are typically a bit higher than the other > bands but that doesn't seem to account for why the lowest band is by far the > worst of them all. > > There are only passives that change from 0-1 MC to the other lower bands and > I'm wondering if it's even possible for those to be the problem but I don't > know of anything else that could be causing it either. > > I think someone suggested that the 1st crystal oscillator's output might be > low for that band but I seem to recall checking that on the scope and output > for the 1st and 2nd positions seems to be very close to the same amplitude > so I'm thinking that might not be the problem. > > Has anyone seen this and possibly have a cause for it? Like I said, I > presume this isn't normal but I don't know that for sure. > > Thanks, > Barry - N4BUQ > ______________________________________________________________ > R-390 mailing list > Home: http://mailman.qth.net/mailman/listinfo/r-390 > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > 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:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
