HI Guys,
I have an intermittent RFI issue that comes from a subdivision about a 1/4 mile
away. To combat the noise I have been trying to use my ANC4 and I built a
sense antenna out of an 80m hamstick that I put 20 feet in the air yesterday
for a trial to cancel the noise on 80m (cheap and easy experiment). The
location of the sense antenna is at the corner of my lot as close to the
subdivision that I can get. The design is the hamstick as a vertical element
and two 102 inch whips as elevated radials.
The noise is s9 on my 1/4 wave 80m vertical and 160m inverted L. This is a
multi band vertical with wires for 40m, 80m & 160m. I also have other
antennas such as a 160m 2wl long loop and a trapped dipole. What is
interesting is that the noise is significantly less on the loop and the dipole.
I attribute this to the noise being vertically polarized based on my research
on the internet. Also this sense antenna is roughly 150ft away from the
vertical antenna.
The issue is the level of the sense antenna noise is significantly less than
the vertical and I am not able to find a null point that makes a difference.
I can however use the loop antenna and I have enough signal with the hamstick
experiment to get a null as the received level of noise on the loop is
significantly less. So I believe I need more receive gain on the sense antenna.
So with the above in mind, is there a low cost pre-amp that I could use on the
sense antenna to boost the signal? Or what other ideas are there for a sense
antenna. I don’t want to put up another 1/4 wave antenna for sensing. I
have read where folks suggest putting 50 ft leg dipole at 5 ft above the ground
for 80m & 40m but I think the noise is vertically polarized and this wont do
much but I could be wrong and have been wrong before.
I have room to try stuff on the property for antenna ideas so that’s not an
issue. However, I need the sense signal level close to the interference level
or I have no chance to get a cancellation of the noise.
Again any and all ideas is greatly appreciated.
~73
Don
KD8NNU
2014 3905CC Top Gun :-)
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