I have a small magnetic loop that's used strictly for receiving. It's a Pixel loop with a preamp (from the same company) and I was astounded at how well it works. I located it about 10 feet up on a rotor, about 50 feet away from the house. It is incredibly broadbanded. While it doesn't quite hear what my K3 hears, it hears surprisingly well across a pretty wide spectrum. I use it mostly for broadcast band DXing, but it also does a pretty good job of keeping track of the county hunter CW net frequencies (40M, 30M and 20M).
The loop is only about 3-feet in diameter - sells for around $400, which included the preamp. The preamp has a switching mechanism I connected to the PTT off our rigs (I share the shack with my wife, who is N4BU). Anything in the shack that trips the ARB-704 relay shuts off the preamp so it doesn't get fried. Art - N4PJ On Thu, May 10, 2012 at 9:10 AM, David Cutter <d.cut...@ntlworld.com> wrote: > I agree about the statement re height above ground which needed > qualifiying a little particularly as they then made measurements somewhat > less than that. The main thrust is about losses and the more removed from > ground and nearby objects the less the loss due to the very high intensity > of the electric field. Not sure if they specified a maximum power handling > and I didn't see anything about inter-plate insulation so it was just dry > air - (ie all the water is frozen on the ground). That probably also means > the ground was not as conductive and lossy as it might be in the summer > when the electrolytes are free to move (my guesswork). Wouldn't work too > well in our wet UK climate! Great piece of analysis and engineering, > deceptively simple. > > David > G3UNA > > On 10/05/2012 11:11, Arthur Burke wrote: > > I bookmarked the site - thank you. However, I didn't get very far the > first time when I saw the comment "....must be 1/2 wavelength above the > ground..." > > Still would like to go back and review the entire article. > > Brings back a humorous dialog from years ago. One ham expressed the desire > to build a "....good, but short, 40 meter beam..." It was suggested he > shorten the beam until it was ultimately a 50-ohm resistor of sufficient > girth to accept reasonable power levels. Chuckles followed. > > Then, someone who apparently didn't pick up on the tongue-in-cheek, > frowned and noted that the 50-ohm resistor would work even better if it was > at least a couple wavelengths in the air. > > Art - N4PJ > > > > On Thu, May 10, 2012 at 7:30 AM, David Cutter <d.cut...@ntlworld.com>wrote: > >> It will be quiet on receive and quiet on transmit, however much power >> you put into it, until it melts, that is. I'd love to know where he >> gets his efficiency figures - perhaps you can ask him. Putting steel >> washers at each aluminium joint turned me off completely along with the >> dinky receiving capacitor. >> >> I'm quite taken by the Midnight Loop from N2APB and N2CX, mainly because >> I built something similar 20 years ago, only a lot bigger! See >> >> >> http://www.midnightdesignsolutions.com/MidnightLoop/Midnight%20Loop%20%28Mar%2011a%29.pdf >> >> David >> G3UNA >> >> >> On 10/05/2012 07:55, Stephen Prior wrote: >> > Hi Fred >> > >> > I have been very tempted by the Alex-loop, but in the meantime have just >> > bought one of G4TPH's loops which I shall put through its paces when the >> > weather improves! I should imagine that the insensitivity to electric >> > fields in the near field would be an advantage in electrically noisy >> > environments. Even a campsite can be very noisy with the inverters from >> RVs >> > and the like spewing out rf everywhere. >> > >> > I'm spoilt for choice of antennas to play with once the KX3 arrives! >> > >> > 73 Stephen G4SJP >> > >> > On Wednesday, 9 May 2012, Fred Jensen wrote: >> > >> >> I haven't been following this thread closely but has anyone mentioned a >> >> small magnetic loop like the Alex-Loop? I've got a good SOTA friend >> who >> >> uses one and loves it. >> >> >> >> 73, >> >> >> >> Fred K6DGW >> >> - Northern California Contest Club >> >> - CU in the 2012 Cal QSO Party 6-7 Oct 2012 >> >> - www.cqp.org >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
