Good advice all around.
More specifics. 1) Study my tutorial app note on this.
http://k9yc.com/KillingReceiveNoise.pdf 2) Study the material on NK7Z's
website. 3) Your spectrum view is FAR too wide to tell much about what
you're seeing. I suggest that you start with 100kHz - 300 kHz views of
the ham bands you care about the most. Then repeat all of your turning
off breakers tests. Do this with the assistance of another ham -- one of
you flips breakers, the other watches the display and changes bands. 4)
Search out and destroy (replace) every switch-mode power supply in your
own home. The average home has several dozen. 5) Repeat steps 1 and 2.
73, Jim K9YC
On 11/10/2018 3:02 PM, David Robbins wrote:
The only thing I can tell from the first few seconds of that recording
are
that the big wide pulses are probably lightning, though there is a
possibility of local power line arcing. It also looks like you are
hearing
lots of actual band activity, sw broadcast and ham and other stuff, hard
to
tell as the scales aren't readable to even know what bands you are
listening
to.
Some general things:
1. You can't clean up the whole hf spectrum so concentrate on the ham
bands.
2. You can't see local noise when the bands are open, so check the high
bands at night and the low bands at midday and when there aren't any
thunderstorms in range.
3. Most of the stuff you'll chase in your house will either be periodic
spurs (harmonics of switching supplies or digital devices) or wide raspy
crap from bad power stuff (if the source is in your house these can be
dangerous, unless it's a furnace igniter maybe), note that cheap high
power
stuff like battery chargers can make noise that wanders quite a bit
4. don't forget to unplug and turn off ups's, their chargers can make
noise
if powered on, and their inverters can make noise if unplugged or if the
breaker is off.
5. Once you have cleaned up your own house then figure out if there are
external noises that are interfering with what you want to hear... if
there
are then you have the harder job of figuring out if they are nearby or dx
sources.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of Andy KU7T
Sent: Saturday, November 10, 2018 21:58
To: rfi@contesting.com
Subject: [RFI] Investigating receive noise - got a few questions
Hi,
I am trying to sort out receive noise issues with my Flex.
I am not exactly sure how clean the spectrum could/should be. I have the
feeling that I may be more concerned about this just because I can see
the
spectrum. I am in an residenial area with 5 acre lots, with miles to the
next town and businesses. I always throught/hoped I have no noise issues.
I took some time last night to turn off all breakers, one after another,
until only the shack was left. Then I reduced everything in the shack so
the
only thing left was the 12V power supply, radio, computer and monitor. I
also adjusted the noise offset on the Alinco Powersupply with no changes,
turned off the computer, and unplugged it. At this point any wall warts,
modems, routers, etc were also off. Still no significant changes.
Take a look here at my spectrum, recorded while I turned off a breaker
every
30 s. There is no difference between beginning and the end:
https://1drv.ms/v/s!AiAwh4TnZjYMhtoFCHwTeJdHO2MFGw
I really have not found any major decreases in hash or noise. Here are
my
questions:
1. Do I go right about this at all? Should I only look at the ham
bands
instead of looking at the half the HF spectrum?
2. There is quite some pulsing/jumping of noise going on below 10 Mhz
(see in video's top spectrum). Are those normal static atmospheric
crashes
or something else outside I should be investigating further and if so
how?
3. There are patterns around 4 - 5 Mhz that are definitely some
patterns
from some device. Is it worth worrying about these, considering there are
not near any ham bands of interest? Goes back to question 1 also: do I
care
whats outside of ham bands?
4. I have some harmonics, some spikes between 12 and 15 Mhz. the
distance
between the spikes is about 17.6khz. Any ideas what that could be? Is
likely
not in my house though.
Any tips and ideas how to proceed?
73
Andy
KU7T
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows
10
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