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101. [Towertalk] limitations of stacking (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Mon, 25 Mar 2002 20:05:33 -0500; Really? Please explain how two identical-pattern antennas, each lossless or with the same percentage of power loss, can have different gains. Better yet, point me to a engineering reference that des; /archives//html/Towertalk/2002-03/msg00639.html (8,080 bytes)
102. [Towertalk] limitations of stacking (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 26 Mar 2002 05:44:43 -0500; Please tell me how, with fixed efficiency, one dipole has gain over another without having a pattern change. Is this like the folklore a double Bazooka or coaxial dipole has gain, or a folded s dipo; /archives//html/Towertalk/2002-03/msg00665.html (8,371 bytes)
103. [Towertalk] MFJ 259B (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sat, 30 Mar 2002 06:54:27 -0500; There are four potential problems. When load impedance gets very high or low (remember it is designed to work around 50-ohm systems), the difference between a reactive load and resistive load is les; /archives//html/Towertalk/2002-03/msg00781.html (7,498 bytes)
104. [Towertalk] Phased Delta Loops (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sat, 30 Mar 2002 06:54:27 -0500; Hi Mark, You are going about this absolutely wrong, unless your main goal is a certain SWR! What you are doing is adjusting the elements and phasing to obtain a certain impedance in the system and l; /archives//html/Towertalk/2002-03/msg00782.html (9,110 bytes)
105. [Towertalk] Phased Delta Loops (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sat, 30 Mar 2002 22:13:57 -0500; Roy Lewallen, without any doubt, is one of the very best EE's I have ever met. Not just in antennas, either. He is also a very nice person. I'm sure anything he has to say is worth hearing or readin; /archives//html/Towertalk/2002-03/msg00795.html (7,130 bytes)
106. [TowerTalk] Antenna Heights and EZNEC (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sun, 3 Feb 2002 09:25:25 -0500; So instead, we assume can use a model and get accurate results 100% of the time that apply to the same situation? Or am I missing something? 73, Tom W8JI W8JI@contesting.com ________________________; /archives//html/Towertalk/2002-02/msg00086.html (10,324 bytes)
107. [TowerTalk] Modeling (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sun, 3 Feb 2002 19:45:16 -0500; I installed a 318-foot tower because the model told me a simple dipole up there would blow away my 3/8th wl vertical on 160. Darn if the vertical doesn't win nearly all the time at any distance! Am; /archives//html/Towertalk/2002-02/msg00106.html (9,120 bytes)
108. [TowerTalk] Antenna Heights and EZNEC (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sun, 3 Feb 2002 19:45:16 -0500; As I recall, Roy Lewallen said he could find little if any verification of ground influences on low frequencies. I think they can to, as long as we remember what models are. My point is this: If we; /archives//html/Towertalk/2002-02/msg00107.html (10,576 bytes)
109. [TowerTalk] Antenna Heights and EZNEC (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Mon, 4 Feb 2002 21:08:08 -0500; I guess then we can ignore things like buildings (with wiring), the slope of the grade, utility lines, and other conductive objects and still accurately predict results within ten feet of effective; /archives//html/Towertalk/2002-02/msg00143.html (9,949 bytes)
110. [TowerTalk] Antenna Heights and EZNEC (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 5 Feb 2002 06:11:07 -0500; Absolutely. That was my point all along. 73, Tom W8JI W8JI@contesting.com ________________________________________________________________________ Where do you get ICE bandpass filters & beverage ma; /archives//html/Towertalk/2002-02/msg00158.html (9,146 bytes)
111. [TowerTalk] W2DU Style Balun (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 5 Feb 2002 19:56:02 -0500; It depends on how much common mode voltage you have across the balun. A minimum rule-of-thumb is to design the balun to handle 1/4 rated power in a test fixture with the ground side reversed on the; /archives//html/Towertalk/2002-02/msg00182.html (10,742 bytes)
112. [TowerTalk] Modeling (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 5 Feb 2002 19:56:02 -0500; 1.) The current induced in the second element by mutual coupling is reversed from the direction of current in the driven element. 2.) If you make it longer than resonance, phase will lag more (it wi; /archives//html/Towertalk/2002-02/msg00183.html (9,269 bytes)
113. [TowerTalk] W2DU Style Balun (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 7 Feb 2002 07:14:38 -0500; I'm sure one 77-material core will not handle 1500 watts (or even less) in all cases, so we have to be careful using that material. 77 material is very low Q, with Q reaching unity below 160 meters.; /archives//html/Towertalk/2002-02/msg00237.html (8,415 bytes)
114. [TowerTalk] Shunt Feed Capacitor for Tower (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 7 Feb 2002 07:14:38 -0500; ......and worse yet they can arc across the insulators. The elements need to be electrically grounded to the boom at the shuntfeed frequency in many cases to avoid arcing. 73, Tom W8JI W8JI@contesti; /archives//html/Towertalk/2002-02/msg00238.html (9,018 bytes)
115. [TowerTalk] Bead baluns (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 7 Feb 2002 08:31:30 -0500; If we have a perfect dipole element mounted on a tower having low common-mode impedance, the bead bead string or balun will have half the feedpoint voltage impressed across the beads. We can simulat; /archives//html/Towertalk/2002-02/msg00240.html (8,700 bytes)
116. [TowerTalk] Isotron (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 7 Feb 2002 18:50:46 -0500; Just when we thought the "don't believe everything you read in an ad" thread was over! To give real near-dipole field strength performance, it would have to be at least 1/4 wavelength long unless th; /archives//html/Towertalk/2002-02/msg00263.html (7,641 bytes)
117. [TowerTalk] Shunt Feed Capacitor for Tower (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 7 Feb 2002 18:50:46 -0500; You can either place a very *high* resistance load there, or a current source set to *zero* amperes. Either will work. Look at the voltage across the load or the source voltage in the appropriate dat; /archives//html/Towertalk/2002-02/msg00264.html (9,377 bytes)
118. [TowerTalk] Shunt Feed Capacitor for Tower (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 8 Feb 2002 19:51:15 -0500; Keep in mind the impedances, and the problem gets easy to solve. The center point of the elements has such a low impedance is makes virtually no difference at all if it is directly grounded. You can; /archives//html/Towertalk/2002-02/msg00296.html (10,584 bytes)
119. [TowerTalk] (the) Actual Capacitor for Shunt-Fed Tower (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 8 Feb 2002 19:51:15 -0500; Coax stub capacitors certainly can work in some applications, but we have to be careful how we use them! Coax makes a notoriously low-Q capacitor, and using capacitance times length in feet is only; /archives//html/Towertalk/2002-02/msg00297.html (9,743 bytes)
120. [TowerTalk] Shunt Feed Capacitor for Tower (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 8 Feb 2002 19:51:15 -0500; For arcing, use peak voltage. Peak voltage is 1.414 times 580 or just over 800 volts. The insulation has to hold off that voltage in all sorts of weather with a safety factor, and any transients or; /archives//html/Towertalk/2002-02/msg00298.html (9,910 bytes)

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