Frank and all, I thought I would share a little real world experience I had today. I have a T, loaded vertical that is only something like 57 feet tall at the moment. The R should probably be in the neighborhood of 10. It is located about 30 feet from the water. I had about 40 radials and they ranged from about 30 feet (ones going straight toward the water or sometimes in the water) and perhaps 75 feet long. I would say the average length is about 60 feet or so. I added 8 more radials yesterday wanting to get the R down to something I liked better. I made a ring out of some 3/8 copper tubing, scraped, soldered, generally made better connections than what I originally had. I moved the R by 1 ohm down from 22 to 21. :-)
Today, despite the fact that "my property" is about 100 feet wide, I first added 6 radials that are well in excess of 100 feet long each - probably 115-125 feet long. The R dropped from 21 to 14. WOW. Then I added 4 more long radials. The R dropped from 14 to 13. I am stopping there. I think I would likely have to add another six going on the neighbors yard to drop it by another 1 ohm. I think I probably just picked up 3/4 dB - maybe that's enough to work the EP6 that I have called for a couple hours. In my particular case, I am not sure I could have reduced the 22 to 13 if I had added another 30 radials x 70 feet long each. The longer ones did the trick in a big way. 73, Happy Thanksgiving and see you this weekend. Stan, ZF9CW On Sun, Nov 18, 2018 at 8:31 PM <[email protected]> wrote: > > Hi Jamie, > > > I use my AA-54 frequently in exactly the manner you're using your > AA-23, I've never had any reason to be suspicious of any of its > readings. I'm lucky to have no AM broadcast stations within ten > miles. > > > Your AA-230 is telling you that at least half of your power is being > lost to ground resistance and need to at least double the number of > radials to significantly reduce your resistive losses. > > > The 2000 feet of wire in your radial system likely would have produced > much better results with twice as many radials of half the radial length > you used. Quarter wavelength radials aren't cost effective until many > more than 60 radials are used. > > > www.w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html > > > 73 > Frank > W3LPL > > > > > ----- Original Message ----- > > From: "Jamie WW3S" <[email protected]> > To: "Topband" <[email protected]> > Sent: Sunday, November 18, 2018 10:33:13 PM > Subject: Re: Topband: Impedance of inv l? > > several have asked how I am measuring the impedance.....I'm using an > AA-230, > and am all the ALL PARAMS setting.....the 230 defaults to a series model, > is > that what I want, don’t see how to change it to parallel. I think the > symbol > for impedance is |Z|, correct? > > -----Original Message----- > From: F Z_Bruce > Sent: Sunday, November 18, 2018 3:20 PM > To: [email protected] ; Topband > Subject: Re: Topband: Impedance of inv l? > > > The far end is high impedance voltage, and has minimum horizontal > current radiation. The inverted L is a good trade off signal vs > available height. Not an expensive antenna to build. > > 73 > Bruce-k1fz > > On Sun, 18 Nov 2018 12:31:38 -0700, Wes Stewart wrote: > > That also drives up the current in the horizontal wire with attendant > increased > horizontal radiation. > > I chose for a couple of reason to do the opposite; shorten the wire to > make > the > feedpoint capacitive and use a shunt inductor to get a 50-ohm match. > This > really doesn't improve the 2:1 VSWR, that I consider acceptable, however. > > Wes N7WS > > On 11/18/2018 8:55 AM, F Z_Bruce wrote: > > That sounds about right. As you put a good ground system under it, > that > value will come down, and the efficiency will come up. > > > > Many add extra antenna wire that pushes the current up the wire, this > also raises the impedance, hopefully to near 50 ohms with the right > length. > > A capacitor (variable, then fixed) in series at the feed point can > cancel the added inductance. > > > > 73 > > Bruce-k1fz > > https://www.qsl.net/k1fz/beverage_antenna.html > > > > > > On Sun, 18 Nov 2018 10:41:36 -0500, WW3S wrote: > > > > What should the Z be for a 1/4 wave inv l, with the radials attached > to > a radial plate? Mine seems to be 60 ohms or so.... > > > > Sent from my iPad > > _________________ > > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > > _________________ > > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > --- > This email has been checked for viruses by AVG. > https://www.avg.com > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
