Re: Topband: 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise
I did a lot of experimenting with this vary problem. I have S9+ noise leverl on 160-30m. I used the MFJ version because I like the ability to control the gain on both sense and main antennas. I tried a 102" whip with the same results as you. I then tried a 25' horizontal antenna and that was less effective than the whip. What I ended up doing was taking a 10' crappy fishing pole and helically winding about 50' of wire starting at the top all the way to about 5" from the bottom of the pole. From there, a single wire goes through the antenna patch panel to the back of the MFJ. I live in a typical suburban area with neighbors about 20' away. I also have a 60KV power transfer station about 100 yards from my home. It took me awhile to get things nulled out. My main antenna for 160/80 is a ladder-line fed 40m loop where I short the feedline together and run it against a bunch of ground radials. Once I got things all worked out, I've run several contests and from the San Diego area, I've been able to work D4C on 160 & 80. I could hear Navassa on 80m but couldn't work them because I didn't know my feedline had broke at 25' long! I've been totally amazed with this noise reduction setup. I can usually get the noise level down to S2 on 160/80/40 and can work everyone that I can hear. My tuning process is to set the sense antenna gain at about S4, then make a note of the setting. I then use the main antenna gain to bring the noise up to S4. I return the sense antenna gain to the written down setting and start using the null until I hear a distinct decrease in noise. I then keep edging up both gains until the noise from the main antenna starts to overcome the sense antenna. I back things down a tad and that's it. Once the MFJ is set, I can move about the band pretty good. Might have to touch up main antenna gain slightly. Anyway, hope this helps! 73 4NEC2 The Definitive Guide: https://leanpub.com/4nec2definitiveguide Website: http://www.ka6wke.net Resume: http://cv.ka6wke.net On Sun, Nov 1, 2015 at 4:01 AM, Goldtr8 (KD8NNU) wrote: > 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 :-) > -.- -.. ---.. -. -. ..- > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise
On 11/1/2015 5:03 AM, Goldtr8 (KD8NNU) wrote: HI Rick I have tried this idea also but again not enough gain on those antennas. The vertical has s9 noise the others are 1/2 that level same as the KD8NNU If you are OK with vertical polarization, the simplest way to null a particular direction is just to use a conventional receiving loop and rotate it until you minimize the noise. (This is a loop in the vertical plane, unlike your 2 wavelength horizontal loop "skywire"). This is a lot more foolproof than the ANC box. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise
HI Rick I have tried this idea also but again not enough gain on those antennas. The vertical has s9 noise the others are 1/2 that level same as the sense antenna I just built. That is why I think I am able to null the loop easily but not the vertical using the hamstick sense antenna. For what its worth, I never was able to null the signal on any of my antennas until I did the trial hamstick yesterday. It was my last attempt and now that I can null the loop I know its possible but it’s the equal signal problem. Thanks Don ~73 Don KD8NNU 2014 3905CC Top Gun :-) -.- -.. ---.. -. -. ..- -Original Message- From: Richard (Rick) Karlquist Sent: Sunday, November 01, 2015 8:45 AM To: Goldtr8 (KD8NNU) ; ham-anten...@yahoogroups.com ; RFI ; tbd...@yahoogroups.com ; topband Subject: Re: Topband: 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise On 11/1/2015 4:01 AM, Goldtr8 (KD8NNU) wrote: 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 KD8NNU Connect the horizontal loop and the trapped dipole to the noise canceller, using one of them as the sense antenna. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise
On 11/1/2015 4:01 AM, Goldtr8 (KD8NNU) wrote: 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 KD8NNU Connect the horizontal loop and the trapped dipole to the noise canceller, using one of them as the sense antenna. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: 160m & 80m RFI issues requesting ideas for ANC4 sense antenna to cancell out local noise
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 :-) -.- -.. ---.. -. -. ..- _ Topband Reflector Archives - http://www.contesting.com/_topband
