[Lowfer] [EXTERNAL] Strange QRM here on SAQ frequency

[Bill de Carle]

Thanks Laurence.  No cable TV in this area but I guess the 
interfering signal could be from some kind of switching supply.  I 
have difficulty with the narrow emission bandwidth and the observed 
frequency stability.  Local phone company runs DSL here over some 
distance so they must have repeaters.  Strange how the signal 
disappears completely from time to time like equipment was switched off.
73,
Bill VE2IQ

At 08:58 PM 7/1/2014, Laurence KL7L wrote:
>Looks like switched mode- get the same from cable company head end 
>amp power supplies in road side cabs - comes and goes
>
>Laurence kl7l
>
> > On Jul 1, 2014, at 4:45 PM, "Bill de Carle" <ve2iq at magma.ca> wrote:
> >
> > Hi Everyone:
> >
> > Anyone on this reflector know what could cause some very strong QRM I
> > see right on top of SAQ's 17.2 Khz frequency?  It consists of a group
> > of spectral lines spaced 120-Hz apart, centered near 17.2 Khz but
> > occupying only about 1 KHz bandwidth.  This QRM is present most of
> > the time at my QTH but oddly enough, it wasn't there on Sunday
> > morning when I got up around 4:30 am Eastern time.  Obviously it's
> > powerline-related, but as far as I know (famous last words!) it
> > doesn't seem to be coming from anything in my home.  I can even
> > disconnect the mains & run on batteries: the signal does not change,
> > so it is clearly radiated, not conducted through the power line.  The
> > amplitudes of the individual spectral lines vary slowly (cycling over
> > perhaps 20 seconds), seemingly at random.  I live in a rural
> > neighborhood and there are some electric fences around.  What bugs me
> > is why at 17.2 Khz?  Have you seen this signature before?  Here's a
> > screenshot showing what it looks like:
> >
> > http://www.magma.ca/~ve2iq/saq_qrm.gif
> >
> > Any ideas would be much appreciated.
> > 73,
> > Bill VE2IQ
> >
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