|[AMRadio] K1MAN comments on disrupting the 75m. AM "Window" (MP3)|
jcandela at prodigy.net
Tue Dec 21 15:35:36 EST 2004
Last night I heard what sounds like DRM on 3880 or
85, and appeared to be 10 kc wide. That was about 9 pm
Central time. It was full scale on my Sony SWL
receiver. Since I am at a new QTH now (Round Rock,
texas) I thought this was local QRN. It was gone this
morning. Now that I read your DRM description, maybe
the AM window has a new problem? Did anyone else hear
BTW I am months away from making RF again. Maybe
easter time. Way too much to do with our move, and
getting the old house ready for the market.
--- Donald Chester <k4kyv at hotmail.com> wrote:
> > > I'm confused on your commentary (The imaginary
> "AM Window" is another
> > > thing that needs to go.).
> I've heard many AM'ers say that many, many times,
> and I agree. The vicinity
> of 3830 is often unoccupied after primetime hours in
> the early evening and
> the SSB'ers go to bed. Sometimes a few AM'ers will
> suggest operating down
> there. For 2 or 3 evenings, an AM group develops,
> and the QSO goes smoothly
> and usually QRM-free, much nicer than the usual AM
> frequencies. After a few
> days, activity dwindles, and finally no more AM
> activity is heard. I tune
> back up to the vicinity of 3885 and there everyone
> is doing their usual
> I sometimes calll CQ on 3830 when it is not busy,
> and most of the time I get
> no AM response.
> Down here, when K1MAN QSY's to 3885, it pretty well
> wipes out any 75m AM
> activity from the Northeast.
> Lately, I have been operating mostly on 160m.
> >I've got Crystals for 3.970/3.980 & 3.990. Isn't
> there some broadcast
> >up in that part of the band, as well?
> It looks like we have lost 3990-4000. For many
> years 3995 has been occupied
> with Radio Deutche Welle. They would broadcast on
> AM, so you could work to
> either side of their carrier unless they were
> exceptionally strong. But
> they recently converted to a new digital mode being
> tested for shortwave
> broadcast use. It is called Digital Radio Mondiale
> (DRM). The signal
> appears as a S0+20dB swath of white noise, with very
> steep skirts. It is
> uniformly noisy throughout the entire 10 kc/s.
> Worse than the old Soviet
> jammers for taking out a wide hunk of the band.
> There is also sometimes one on 40m, in the vicinicy
> of 7260.
> Wait tilll all the major SW broadcasters convert to
> this mode.
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