[AMRadio] K1MAN comments on disrupting the 75m. AM "Window" (MP3)


Donald Chester k4kyv at hotmail.com
Tue Dec 21 13:50:41 EST 2004



> > 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 
thing..

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 
>station
>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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