Hi Jim and gang.
I think everyone here is right. The point being that it really is most
important to track down what property the RFI is originating from and then
you can figure out exactly what device is generating the RFI. In this
recent case I did look at the spectrum display recording of the RFI that
N9CJT was experiencing ahead of time (before I traveled to his QTH) and I
asked him if the RFI was present 24 hours a day or not and if weather
influenced it before I scheduled a visit. One big reason I asked this (but
I always ask this) is that K9CJT lives about 65 miles from my home and if I
travel there I needed to be 100 percent certain the RFI would be present
when I was there.
I also always ask what frequencies/bands he is experiencing the RFI as this
is also very helpful to me, especially when it involves multiple bands.
The only reason I want to know if the RFI is impulse noise (like power line
noise) before leaving my home is that I will then make sure I also pack my
VHF and UHF direction finding gear but even in this most recent case and in
almost every case I pack that gear too just because I never know what
unexpected things I will encounter and I tend to be obsessive compulsive.
I also pack duplicate receivers and preamps to avoid having to make
additional trips and I also check my cables with my NanoVNA before leaving
my house to make sure everything is working properly.
Jim (K9YC) mentioned “NK7Z's excellent method of 24 hour recordings
revealing WHEN the noise is present lets us know WHEN to chase it.”, but
what I have found is that the typical ham that contacts me for assistance
(which I do absolutely free) really does not have that kind of technology
available so they have to very manually keep track of the RFI versus time
of day and weather conditions for me which then helps me formulate my
plan. But Jim is absolutely correct that this information is vital to me.
Just FYI,
Don wd8dsb
On Sun, Sep 10, 2023 at 3:05 PM Jim Brown <jim@audiosystemsgroup.com> wrote:
> I strongly disagree. The FIRST thing we should do in chasing noise is to
> determine whether it is impulse noise (mostly power line) or electronic
> noise, of which this is an example. Once that is determined, NK7Z's
> excellent method of 24 hour recordings revealing WHEN the noise is
> present lets us know WHEN to chase it. And when multiple sources are
> present, it can prevent us from getting confused.
>
> I DO agree that trying to determine specific sources from their spectrum
> is a fool's errand.
>
> 73, Jim K9YC
>
> On 9/10/2023 9:09 AM, Alan Higbie wrote:
> > Don’s approach in this case is a good example of first focusing on WHERE
> IT
> > IS.
> >
> > Imagine how much time they saved by simply locating and sniffing out the
> > source.
> >
> > Trying to determine WHAT IT WAS by looking at the SDR, how it sounded and
> > researching databases would have only added time and delayed elimination
> of
> > the RFI.
>
>
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>
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