[Elecraft] RFI issues

[Lyn Norstad]

Thanks for that, Jim.

We are actually 38 miles due West of the Willis (Sears) tower in Central
Kane County.  There is virtually no industrial noise source nearby, but we
do occasionally get interference from medical apparatus.

With my 360 ft. EDZ (cut for 3.5 MHz) strung E-W at about 30 feet, I
normally have a background noise level in the S1 - S2 level, depending on
band and time of day.  I have a backup antenna in the attic (modified G5RV)
that does not fare quite as well, but is still useable.

Approximately 10 mi SW of us is a different sort of problem.  A commercial
shortwave station has been built and is operating on an experimental basis.
Their plan is to transmit market data over the pole to High Speed Traders in
Europe (milliseconds faster than cable).  They are currently licensed on
frequencies on both sides of our 40 meter band, and between our 30 and 20
meter bands.  They are using a 25 KW transmitter into an 18 db gain curtain,
with an EIRP of 808 KW.  We are located on the edge of their 38º beamwidth.
To date I have only seen them in the region just below 40 meters.  To say
they are noticeable would be an understatement.

There are quite a number of similar stations across the country, so I'm sure
others in the group have encountered them as well.

73
Lyn, WØLEN


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim Brown
Sent: Saturday, February 22, 2020 12:45 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] RFI issues

On 2/21/2020 6:12 PM, Lyn Norstad wrote:
> In Chicagoland, all wiring must be in conduits, and both the
> kitchen and the shack are on their own circuits.  In fact, the only 'home
> grown' RFI I am aware of is 1 out of 4 identical HP 24" LED monitors that
> puts out a steady carrier on 30 meters.

Having lived in Chicago for 42 years and maintained an engineering 
consulting practice there for 30 years, and as a former member of IBEW 
134, I'm well aware of the conduit requirement. :) Indeed, I had a lot 
of conduit installed in the 2-flat I bought on the North Side in 1986. 
Which is also why I added the phrase "the nature of electrical wiring in 
your home also matters." The large sound systems I designed and 
specified used miles of conduit for both power and signal wiring. When I 
moved to W6 in 2006, I had the outbuilding that would become my shack 
and consulting office wired with EMT before I moved in.

Several other points here. First, RFI is generally NOT conducted on 
wiring from one piece of equipment to another, it is radiated by wiring 
from one piece of equipment to another. And it is often present on, and 
radiated by, the equipment ground conductor (the green wire). Properly 
installed conduit (continuous and bonded at every junction and at both 
ends) provides shielding, and prevents radiation.

Second, when I operated in Chicago, my noise level was fairly high, with 
contributions from my own home, my tenant who lived below me, the homes 
that surrounded mine, Newark's corporate office building at the end of 
my block, whatever was on power lines, and trains on the Northwestern 
track across the street. With that noise level, usually in the range of 
S6 to S8, it would be pretty hard to notice yet another noise source 50 
ft  from my antennas.

73, Jim K9YC
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