[OKDXA] Radios and noise

[Kim Elmore]

A new radio is unlikely to effectively deal with the noise you hear. 
There could be many sources: it could be a plethora of small switch-mode 
power supplies (SMPS) in your own home. If you can manage it, kill power 
at your house at the main breaker and see if the noise decreases. If it 
does, you can then look for the various possible sources.

You didn't mention the antenna you use, but I know that on 40 m, I often 
see noise levels like what you describe on my 2 el yagi up ~50 ft when 
the band is open. You'll likely see variations between day and night. 
Here's a quick way to determine if your RF environment is quiet (little 
man-made noise): record your daytime noise level on a low band (80 or 
160 m), then do the same at night (ou don't need a resonant antenna for 
this check). If you hear more noise at night than in the day, you're in 
a quiet place. Why does this work?  Sferics from lightning will 
propagate at night but be absorbed in the daytime. If you can hear them 
at night based on an increased noise level, you're in a pretty good place.

73,

Kim N5OP


On 1/23/2017 7:07 PM, John Geiger wrote:
> I know if you buy a more expensive radio, you get a receiver that (usually)
> has better dynamic range and handles QRM conditions better, generating less
> IMD products and blocking when the band gets full of signals.  Does the
> same hold true for QRN and electrical crud?  I know that some radios have
> more tools than others, like noise reduction, notch filters, stuff like
> that.  Do more expensive receivers get less affected by RFI and other junk,
> and by atmospheric noise?
>
> Here is my situation:  I was having some bad powerline noise from a pole
> close to my house. The noise blanker in the radio I have took out the buzz,
> but I am seeing a S6 noise level on 40m SSB and on 20m SSB sometimes.  I
> figured some of that came from the line noise, so I didn't think about
> doing much until the line noise was fixed first.  Well the power company
> came and fixed it today. The buzzing is gone!  The noise level still is
> there, though.  I am using a Yaesu FT100D which has a great noise blanker,
> and does have AF DSP, but it is a cheap, mobile type HF/VHF/UHF radio.  On
> 40 meter SSB I see a S5 or S6 noise level when on SSB, and that is with the
> preamp off.  On CW it is much less because I put the 500hz CW filter in
> line.  20 meters is sometimes the same, but sometimes on SSB the noise is
> much lower, which I think is probably from urban crud. I live in an older
> neighborhood where the houses are maybe 8 feet apart, if that much. I am
> sure many neighbors have switching power supplies in all sorts of
> electronics.
>
> So, is this 40 meter noise level pretty typical for most people?  Would a
> more expensive radio like a Kenwood TS590 (which is supposed to have a
> great receiver), Yaesu FTDX1200 or Icom 7200 be less affected by these
> types of noises?  I can't afford much more than that right now,and would
> like something that is fairly small enough to still take mobile or portable
> from time to time.  I did try a yaesu FT891 which is a mobile sized radio
> and it was maybe very slightly better, but not really noticable.  A Ten Tec
> Eagle would also be small enough.
>
> Is this one of the compromises you have to live with when you get a smaller
> radio?
>
> 73 John AF5CC
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-- 

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in 
practice, there is." //– Attributed to many people; it’s so true that it 
doesn’t matter who said it./