Geoff -- Your situation sounds worse than mine, trying to DX the medium waves from a small suburban lot. There are enough noise sources in the house (which I can't control) that I can't use an indoor loop. I've had good luck with a pennant antenna aimed at Europe/North Africa, with a low noise amplifier and a line isolator located at the antenna.
Another antenna that I had good luck with was a horizontal square, of the design written up in QST, September 1995, "A Receiving Antenna that Rejects Local Noise," by Brian Beezley. On the 90 meter shortwave BC band, I could hear audio on Indonesian domestic stations that were barely producing hetrodynes on other so-called low-noise antennas. It's important to get the antenna perfectly horizontal and as far from the house as you can. This antenna has to be resonated for the band you're using, so it could be a problem on MW, where the top frequency is 3 times the bottom frequency. You'd probably need a remote tuner, maybe using a varactor diode. Good luck! --Art Delibert, KB3FJO > From: [email protected] > To: [email protected] > Date: Sat, 12 Feb 2011 21:56:12 +0200 > Subject: [Drakelist] SPR-4 medium wave antenna? > > I live in a "sea" of electrical noise and need an antenna for the > SPR-4 for AM broadcasts. I tried to duplicate the loop that was made > for the SPR-4 using RG-6 and it simply did not work. The broadcasts > were weaker than the noise. Even using the loop (with my HF antenna > disconnected) the noise was stronger than the calibrator. > > So I need to locate antenna outside the noise, which means I need to > use about 10 meters of coax. Due to availability and price, I've > decided to use RG-6 coax. I can run an antenna at about 6 feet above > ground level (in a valley) and a maxiumum of 11 meters long. > > What should I use? A dipole? An end fed wire? If I use an end-fed wire > what do I ground? Should I make a 9:1 or other transformer? I have > several sizes of Russian made ferrite rods with a permeability spec of > 400. I only have #24 stranded plastic insulated and 1mm solid plastic > insulated wire. > > Should I connect the coax to the antenna input or the loop input? > > The receiver is on the second floor. At the far end of the antenna is > an HF vertical that goes to the first floor, and there is a ground rod > there. If I do ground the coax or use a transformer, I can either run > an extra 10 meters or so and put it near the ground rod (and other > antenna), or put it closer and run a 10 meter 1mm solid wire to the > ground rod. > > Thanks in advance for any advice. > > 73, > > Geoff. > > > -- > Geoffrey S. Mendelson, N3OWJ/4X1GM > Those who cannot remember the past are condemned to misquote it. > > > > > > > > > > _______________________________________________ > Drakelist mailing list > [email protected] > http://mailman.zerobeat.net/mailman/listinfo/drakelist > _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
