I would like to know more about your receive antenna. At my home, I deal with S7-S9+ noise and am looking for some way to be able to operate besides FT8.
Thanks… David Thompson, AG7TX Jack of All Trades Master of None [email protected] > On Oct 28, 2019, at 14:31, Drew AF2Z <[email protected]> wrote: > > My RX antenna is a pair of small amplified stacked loops. It uses the LZ1AQ > amplifier board fed with common FTP (foil twisted pair) cable, which provides > the supply voltage, control lines and a shielded twisted pair for the signal. > I don't think you can get any better noise isolation than that. > > It is a lot quieter than my transmitting antennas; lower signal levels as > well, but often a better signal-to-noise ratio than the transmit antennas. > > 73, > Drew > AF2Z > > > On 10/26/19 10:11, Victor Rosenthal 4X6GP wrote: >> Jim, >> I have to disagree about balanced line. Unlike coax, both conductors are >> exposed to external RF fields, so common mode noise will be rejected. If the >> antenna and line are properly balanced (not always easy to do, I admit) and >> if it is fed through a balanced antenna tuner, there is no reason for it to >> be noisier than coax. Yes, it can't be choked, but it doesn't need to be. >> My antenna is a 10m long rotary dipole fed with open line. It has gone >> through several iterations and I've been very careful to install the line so >> that it is perpendicular to the antenna for as far as possible, etc. I've >> tried various balun arrangements, but the system that works best, both for >> reducing RF in the shack when transmitting and noise immunity when >> receiving, is a Johnson kW Matchbox. >> There is a building taller than mine a few hundred meters away from it, and >> a very distinct noise peak when the antenna is turned toward it, which seems >> to indicate that the noise is picked up by the antenna, not the line. I >> notice the same noise peak with a coax-fed shielded loop antenna, so it is >> definitely coming from the building, and isn't an artifact of the alignment >> of the antenna to the line. I am pretty sure I have at least a 10 dB >> difference in noise when a band is open (at least, when the antenna is not >> aimed at that building), but I will wait until the band is solidly dead >> tonight to check that out. >> My pattern is a form of figure 8 on 40-10 meters, but you are right that you >> can't maintain the pattern over a greater frequency range. >> My main point is that there is nothing inherently noisy about a two-wire >> transmission line! >> 73, >> Victor, 4X6GP >> Rehovot, Israel >> Formerly K2VCO >> CWops no. 5 >> http://www.qsl.net/k2vco/ >> On 26-Oct-2019 10:32, Jim Brown wrote: >>> On 10/25/2019 2:01 PM, Bob McGraw K4TAX wrote: >>>> Except for my 6M yagi, all of my antennas are non-resonant antennas. My >>>> favorite is the 256 ft center fed wire {resonant at 1.825 MHz} with a >>>> balanced feed. >>> >>> Dean Straw, N6BV, retired editor of the ARRL Antenna Book and Antenna >>> Compendiums, is a very smart engineer and a very good friend. But his >>> promotion of this sort of antenna is probably the greatest error of his >>> time in that job, an idea whose time is LONG past, for many reasons. >>> Primary -- 1) it cannot be choked to kill noise on RX, and 99.9% of hams >>> live surrounded by local noise and 2) it's pattern is different on every >>> frequency. >>> >>> I am a strong believer in resonant antennas for each band, if if the must >>> be multi-band antennas like fan dipoles to fit in the available space. For >>> example, a 20/15/10 fan fits in 33 ft and works great, with a predictable >>> pattern on each band. An 80/40 fan works on 15M, with a predictable pattern >>> on both 80 and 40. Hypower Antenna company sells loaded antennas that are >>> resonant on 80 and 40 and fit into about 100 ft; I used one in Chicago on >>> 30 to great effect. All of these antennas are fed with 50 or 75 ohm coax, >>> and CAN be choked to kill RX noise. >>> >>> RX noise is a VERY big deal -- if you can't hear 'em, you can't work 'em. >>> If you haven't worked to minimize your RX noise, you're DXing with one hand >>> tied behind your back! My friend AG6EE goes to remote locations in NV, OR, >>> and CA to light up rare grids with 1kW on 6M. Folks trying to work him >>> complain of one-way propagation because he hears them really well and the >>> don't hear him, but the REAL problem is their local RX noise. >>> >>> http://k9yc.com/KillingReceiveNoise.pdf Text, NCJ article >>> http://k9yc.com/KillingRXNoiseVisalia.pdf Slides Visalia talk >>> >>> 73, Jim K9YC >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
