[time-nuts] Re: Syncserver S300 LFR 60 kHz WVVB

[Bob kb8tq]

Hi

The tendency is to not point fingers at specific devices. They
are *all* supposed to be adequately filtered to prevent any
interference. 

Point to this or that in your paper, you start one down the trail that
might lead to legal proceedings. Since those sort of proceedings
are properly in the jurisdiction of specific parts of specific agencies,
stepping on toes is a very real possibility.

What you normally see in papers is a generalized statement. 
Something like “interference in urban areas has gone up by
20 to 40 db over the last 2 decades”. No that’s not a direct 
quote from anywhere. Don’t take those numbers as factual. 

Simply hearing / seeing RFI is pretty easy. Anything that will
hear or display RF in the target range likely can be used for the
task. Doing *calibrated* measurements is a bit harder than a 
simple look see. 

Some folks like portable spectrum analyzers. They might need
a preamp in front of them. Depending on the make / model ( = price )
they may have a few ( or quite a few ) internally generated signals 
you need to sort out. They have the benefit of showing a lot of data
all at once. Switchers move around as they adapt to things.

Antenna wise, something directional is nice for working things out. 
A ferrite rod is pretty common in the 40 to 80 KHz range. There are
other antennas that could be used. If calibration is what you are 
after, that likely will dictate very specific antenna designs. 

Typically the problem isn’t looking and finding nothing. It’s finding 
so many issues that you can’t sort them all out. This or that LED bulb 
puts out crud. You have 30 of them in your home. Next door has
another 30 and so do the folks across the street. ( We all got them 
when they went on sale …. :) ). 

Once you find this LED bulb what do you do? You could head out and buy
one of every brand at the local store. Bring them home and see how
they each do. Maybe you buy a couple of each to be sure. Do you then
buy a bunch of the “good ones” for all the neighbors? What about
when the "good ones" start going nuts a year from now …. 

Yes, I’m picking on LED bulbs. That’s not because they are the only
thing out there that might produce RFI. Switchers are everywhere. 
The gizmos you find could be just about anything that plugs into the
wall. Those “wall wart” power supplies could just as easily been used
as an example. 

Yes, this is only one of many rabbit holes you can go down in this 
area. There are a lot of directions you can go and measurements you
might try to make. In the target case of keeping your WWVB radio 
running, they pretty much all lead to frustration …..

Crazy

Bob

> On Sep 4, 2022, at 11:20 PM, Hal Murray via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> 
> Bob kb8tq said:
>> As time has gone on, the world has fallen in love with switching power
>> supplies. Often these run at 40 to 80 KHz and create a ton of RFI. That has
>> made WWVB more difficult to receive. Also MSF propagates into  the northeast
>> at some times creating issues as well.  
> 
> I remember a rant from Dave Mills many years ago when his WWVB gear was no 
> longer working well.  I couldn't find it via google.
> 
> My memory is that he had tracked down the interference to EMI on the power 
> lines coming from a local factory.  I don't remember how far away it was.  I'm 
> guessing it was 1-3 miles, maybe 5-10.
> 
> Has anybody seen any reports of this sort of problem?  Did NIST publish any 
> data when they were researching the new modulation scheme for WWVB?
> 
> If I want to measure EMI around my neghiborhood, what sort of gear would I 
> need?
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
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