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
