[RFI] 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise

Goldtr8 (KD8NNU) goldtr8 at charter.net
Sun Nov 1 07:01:30 EST 2015

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.  

2014 3905CC Top Gun :-)
-.- -.. ---.. -. -. ..-

More information about the RFI mailing list