[RFI] "Quiet" RS 75 watt inverter

[Dale]

Ken and David,

Getting to a low residual noise level on 40 thru 160 is not easy, for sure.  However, it is possible and I guess I am among the fortunate to have achieved that, although I have sincere doubts as to longevity of that achievement.  As far as I can tell, getting levels below S-5/6 or so are very difficult to achieve in even small towns these days.  There are just too many gizmos and gadgets out there that help keep the noise floor up (and rising!).  

The situation is this (as an example of what it takes to get low environmental noise on those 3 bands:  The antennas are situated near the center of a 5 acre parcel in the middle of corn and soybean fields.  There are no power lines parallel to the antennas any closer than 1/4 mile for E-W and 1 mile for N-S.  My house is on the end of a branch feeder line and the last pole, with above-ground pole pig for my house, is at least 350 to 400 feet from the HF wire antennas.  The branch feeder line runs away from the house towards the main distribution E-W line that is south and 1/4 mile away.  

I do not share the pole pig with any other residence, and my 3 neighbors (across the road, south on same side of road, north on same side of road) are at roughly 500 feet, 600 to 700 feet, and 1000 feet (in that order) from the antennas.  My neighbor to the north of me, on the same side of the road, gets his power via a different power company(!) and his lines are probably 1500 feet from me, running northward and never coming close to my property.  Yes, all of us out here are on separate pole pigs (some on poles, some ground mounted). 

In the winter, nominal residual noise is S-0 to S-2 on those bands, slightly higher in summer due to atmospherics.  I noticed this past weekend that my 75/80 meter noise is now about S-1/2, depending upon time of day.  I frequently participate in the Iowa 75m traffic net held at 12:30 PM local time Mon - Sat, when there is lots of absorption and the band is "dead".  Yep, weak sigs, but I can hear nearly all of them (from across the state) with my 75m full size inverted-V (apex at 32 feet) that runs E-W, and I hear them equally well on either my Alinco DX-70TH (without the pre-amp) or my (it's OK to laugh) Heathkit HW-12 monobander from 1967.

I have had 2 instances of bad RFI related to power line fundamental frequencies since moving here 14 years ago.  First, an electric fence was being contacted at random times by tall weeds.  That was 1/4 mile away and hit 40 thru 160 pretty hard.  The problem went away when the property owner cut the weeds to sell the place, plus the new owners appear to not be using an electric fence.  The second incident, far worse, was caused by a broken grounding wire on a power line lighting protector located about 1 mile east of me.  That one wiped out all of the AM b'cast band plus 40 thru 160.  The racket was 20 over 9 on 160 and still S-8/9 on 40.  That got fixed when I found the pole and the power company came out (same day) and took care of the problem.  Silence since.

So, it is possible, not easy, and can be wrecked in short order by problems with power distribution equipment or major league noise makers that may come along with new farming equipment or a new industrial user somewhere on the main line.  (The distribution lines that are 1/4 mile south of me are 3-phase, with some farms and at least one small industrial wood working operation connected to those lines.)

Because so many variables are involved, YMMV, and good luck.

73, Dale
WA9ENA     
         



-----Original Message-----
>From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
>Sent: Mar 24, 2014 3:10 PM
>To: David Robbins <k1ttt at verizon.net>, rfi at contesting.com
>Subject: Re: [RFI] "Quiet" RS 75 watt inverter
>

>
>> Believe it or not there are hams with noise levels on the 
>> order of S2 at times.
>
>Oh, yes, but that can also depend on the band.
>
>I don't know too many hams who have an S-2 noise level on 80 though.
>
>Most people I have talked with "enjoy" a noise level of about S-5 to S-7.
>
>I was talking with one friend who lives out in the woods and uses battery 
>power who, apparently, hears things that none of the rest of us do due to his 
>extremely low noise level.
>
>Sounds like Heaven to me.
>
>Ken W7EKB