I am somewhat new to 160 meters. I converted an old VHF tower at my house to
a 160 M 1/4 wave radiator in late 2013 and have been active since then on a
casual basis. Recently I started showing symptoms of the 160 Disease, and
have been looking for ways to improve things. The XYL has nixed anything big
(no more towers) so I am stuck with a single radiator, but I can still work
on the receiving side. I just built up an Africa beverage (100 degree az)
and was happy with the noise level on that antenna. It seems extremely low
and about as good as my Europe beverage. Recently, I tried measuring each
beverage and the vertical antenna to nail down the noise floor using my K3
and P3 panadaptor. I wonder if these numbers are good and how they compare
with other setups. For the record, I set the P3 at the narrowest span, 2
kHz. I used the preamp ON for the beverages and the preamp off for the
vertical. I recorded these levels on late Saturday evening during the ARRL
160 contest, and then again, the following Monday during the day. I
recorded the following numbers...
ANTENNA NOISE LVL DAYTIME
JA 330 deg -133 -138
West 270 deg -125 -130
SW 220 deg -125 -132
Africa 100 deg -136 -144
Europe 45 deg -138 -142
Vertical Antenna -115 -123
All measurements were taken with the P3 panadaptor set at 2 kHz span. That
is important. K3 preamp is ON. These numbers taken at night are a moving
target. The noise can vary from hour to hour. I looked across the 2 kHz span
of the P3 and averaged what I saw. I seem to hear reasonably well with the
vertical, and in the past used it quite often. Now that I have a few
beverages, I hardly ever listen on the vertical anymore. Both the 220 and
270 degree beverages suffer from power line noise and are 10 dB noisier than
the wires aimed East. I am thinking about maybe nulling out the power line
noise. I am sure that noise is killing my receive.
I guess I should make a real measurement of my noise floor at a
specified bandwidth of the receiver. That would require more work! I took
the easy way and set the P3 at minimum span and looked at the "grass level".
What numbers do others see on 160?
I live in a rural area in Maine near the NH border. I have a neighbor
across the street and another two about 1000 to 1200 ft away. I think my
location is pretty quiet, but I do often see interference that comes and
goes. I always hear two electric fences. One is a single snap every second
or so. The other is a pulsing burst of noise that lasts maybe 300 ms that
repeats every second or so. There is also a rather broad drifting signal to
my NE that is about 20 kHz wide and drifts around 1820 kHz. It is about 5 dB
above the normal noise. I suspect it is a mile away, but have not found it
yet.
Dave K1WHS
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