Hi Jamie,
I forgot to mention that nearby conductive objects, especially nearby towers can significantly affect the base impedance of a vertical. Nearby on 160 meters is about 200 feet... 73 Frank W3LPL ----- Original Message ----- From: donov...@starpower.net To: "Topband" <topband@contesting.com> Sent: Monday, November 19, 2018 1:31:27 AM Subject: Re: Topband: Impedance of inv l? 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" <w...@zoominternet.net> To: "Topband" <topband@contesting.com> 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: wes_n...@triconet.org ; 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