QRN In The Grass
From Daryl Stout
@618:250/1 to All
on Tue Jul 28 00:04:58 2020
This is from the March, 1999 issue of WAVELENGTHS, the Arkansas Radio Emergency Services Club newsletter. The article is ECNALG -- a Backward
Glance -- articles written by our senior or posthumous ham friends. This
one was also written by Lyle Armstrong, K5VPM, who became a Silent Key
in 1998. I personally remember when this happened, and it was, indeed,
a very interesting experience!! DS
"QRN in the Grass" by Lyle Armstrong, K5VPM
About the time a fellow figures he knows about all there is to know
about QRM - QRN - QSB, and what causes the sounds he tunes in or out,
something happens that doesn't add up, and the book solution doesn't
fit. It's exasperating.
My ham shack is located in the attic of my house. I have the usual
assorted dipoles and inverterd V's that cover the HF bands, and an 8
element telex 2 meter beam. Like most fellows I meet on CW, 25-30 feet
seems to be the average antenna height the majority of us are stuck
Well, one evening, I was trying to contact my brother, KA8CKL in
MIchigan, on a 15 meter schedule. The whole band was weird. There were
strange harmonies and high pitched squeaking sounds. They all blended
together, and were strong enough to block almost all CW signals...and
what CW I could tune in was distorted and weak.
I called W5ZXS, and asked him if he noticed anything unusual on 15.
Jolly said no...it was not open, but that was not unusual.
I was so intrigued by the strange sounds I spent the night checking
the rig and all electronic equipment in the house...even shut off the
VCR, TV, answering machine, microwave, and even the FM-AM radio. Then I
shut off the fluorescent lights and the mercury vapor night light; I
imagined that made a slight blip in the sound of the continuing
background noise mess.
The scope showed definite sudden voltage peaks of different levels,
and at uneven intervals. A tour of other bands revealed the fact that
this freak interference covered all the HF bands. The "crud" was louder
on 15 meters, but was audible on all HF bands, but not subject to being
tuned out. I even tried a 12 volt DC HF receiver, and it yielded the
Along about 2am, I checked into the Fertilizer Net, and even that
brain trust group couldn't offer any answer to my problem. One regular
member suggested I change brands. Finally, I checked out and went QRT.
In the light of day, I tried again...still there, but weaker. NUTS!!
I shut it all down, and fired up the mower and tried to cut the grass,
which had been growing freely because of the rain and sun cycle. It was
all the 5-horse Briggs and Stratton with a 21 inch blade could
handle...but it had to be done, wet or not. So, I did it. The whole
yard covers 175 x 200 feet around the house...it just about did me in.
About 5pm, I finished the job, cleaned up, crawled up the stairs to
the shack, turned on the TS520S, flipped it to 2125 CW, and man, oh
man!! No QRM - QSB - QRN or strange stuff at all!! Just a Cincinatti
station calling CQ. I answered him - good QSO - 73, CUL.
Well then, a check of the other HF bands revealed nothing abnormal. So
what was it all about, anyhow?? Well, I finally figured it out...here is
my diagnosis of the phenomena:
1) The unexplained noise was at my QTH.
2) It stopped as soon as I cut the grass.
3) Nothing else was done at my QTH.
I figure that the grass was growing as fast as nature would allow. The sun-and-rain-and-sun-and-rain cycle cause the grass to grow at MORE THAN
its maximum natural rate...and it was such an ideal growing condition
that the molecules built up faster than the growth could occur. Then,
this energy stress would discharge through the vascular bundles to the
ground, and in so doing, would radiate a quick RF wave. The varied
species of grass in my yard would account for the different levels and frequencies of RF emitted.
As a boy in Nebraska, I remember that on a hot, still night...a fellow
could stand in a cornfield, and every few moments, could hear a loud
squeak as the growth stress molecules would expand. The corn would grow
in inch or two a day, but only at night when the wind died down could
the jump in growth be heard. I just know that if I had a means of
receiving and indicating some RFI, I would have seen the needle kick
every time the corn squeaked.
I don't know enough about the super advanced electronics or solar
phased agronomy to figure out any other solution that will fly.
Finally, if you want to enjoy the hobby at its finest, keep your grass
cut short. And anyhow, why else is the green wire for ground?? Also,
perhaps my grass grows so fast because of some unknown RF feedback from
the Fertilizer Net frequency.
Submitted subject to review...
Lyle E. Armstrong, K5VPM, SK
* Synchronet * The Thunderbolt BBS - tbolt.synchro.net
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (618:250/1)