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101. Re: Topband: Spark gaps (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Fri, 27 Jul 2012 09:43:30 -0600; www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm Ross recommends carbon for lightning. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK; /archives//html/Topband/2012-07/msg00368.html (9,812 bytes)
102. Re: Topband: Spark gaps (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Fri, 27 Jul 2012 13:42:42 -0600; _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK; /archives//html/Topband/2012-07/msg00371.html (10,028 bytes)
103. Re: Topband: Spark gaps (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Fri, 27 Jul 2012 14:42:06 -0600; Mike, here it is. The resistivity of amorphous carbon is 35 u ohm meters (That's a 1 meter cube) A 1" cube has a resistivity of 1.4 m ohms, a one inch sphere about 3 m ohms. 100 kA for 20 us dumps 60; /archives//html/Topband/2012-07/msg00374.html (11,454 bytes)
104. Re: Topband: Spark gaps (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Fri, 27 Jul 2012 16:04:05 -0600; I do make (all too frequent) mistakes so check away. Carbon is 2000 times more resistive than copper. Being more resistive the carbon skin depth at lightning frequencies is much deeper than copper or; /archives//html/Topband/2012-07/msg00379.html (9,719 bytes)
105. Re: Topband: Spark Gaps.. (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Sun, 29 Jul 2012 11:33:07 -0600; Bob, that an excellent idea! _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK; /archives//html/Topband/2012-07/msg00390.html (6,959 bytes)
106. Re: Topband: elevated counterpoise and lightning (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Mon, 30 Jul 2012 09:40:07 -0600; Bob, do you have ground rods for lightning? The stub should be ok for static discharge but not for near or direct strikes. _______________________________________________ UR RST IS ... ... ..9 QSB QS; /archives//html/Topband/2012-07/msg00400.html (8,102 bytes)
107. Re: Topband: U think you've got interference (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Tue, 31 Jul 2012 14:47:26 -0600; No, the military is not using tubes except for the occasional TWT high power amplifier. When specified for EMP military gear will take it. _______________________________________________ UR RST IS ..; /archives//html/Topband/2012-07/msg00420.html (7,513 bytes)
108. Re: Topband: FCP model (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Wed, 1 Aug 2012 09:43:09 -0600; For a short vertical I prefer ground radials over an elevated counterpoise because the counterpoise height reduces the monopole length. _______________________________________________ UR RST IS ... .; /archives//html/Topband/2012-08/msg00007.html (8,053 bytes)
109. Re: Topband: Radials over a stone wall (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Fri, 10 Aug 2012 10:19:52 -0600; I can run a NEC simulation tomorrow to see how much radials up and over affect things. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK; /archives//html/Topband/2012-08/msg00152.html (9,568 bytes)
110. Re: Topband: Radials over a stone wall (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Fri, 10 Aug 2012 10:44:22 -0600; Simulation will tell the tale but in the mean time we have two things caused by the up-and-over that we can mull over: 1) There is cancellation of the magnetic fields by the up-and-over wires thereby; /archives//html/Topband/2012-08/msg00155.html (10,876 bytes)
111. Re: Topband: electrical wavelength (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Mon, 10 Sep 2012 17:42:33 -0600; Run the numbers and for RG-6 we see that sq root of L/C is good above a couple hundred kHz. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK; /archives//html/Topband/2012-09/msg00046.html (11,946 bytes)
112. Re: Topband: RX epiphany? (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Thu, 13 Sep 2012 19:44:31 -0600; Bob, with US and European stations operating top band during the winter only you will only work them during your summer. So, you will always be subject to higher noise at your end of the path. Dave _; /archives//html/Topband/2012-09/msg00083.html (9,858 bytes)
113. Re: Topband: RX epiphany? (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Thu, 13 Sep 2012 20:03:46 -0600; Bob and Bob, so it is! I thought it was just below the equator. Dave _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK; /archives//html/Topband/2012-09/msg00085.html (11,060 bytes)
114. Re: Topband: Short radials? (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Thu, 27 Sep 2012 19:32:37 -0600; Real data: I am presently using a 30' base loaded vertical. The ground system consists of 90 radials from 12 to 25 feet. The base referred ground loss is 10 ohms. ____________________________________; /archives//html/Topband/2012-09/msg00304.html (11,752 bytes)
115. Re: Topband: Short radials? (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Thu, 27 Sep 2012 20:18:52 -0600; Tom, with this ground system and 90 degee monopoles I measure 5 ohms ground loss on 7 to 28 MHz. With the 30' vertical I measure about 10 ohms on 1.8 and 3.5 MHz. The 7 MHz measurement agrees with th; /archives//html/Topband/2012-09/msg00308.html (9,852 bytes)
116. Re: Topband: Short radials? (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Thu, 27 Sep 2012 20:50:57 -0600; The maximum base-referred ground loss number my system has is bounded at 0 and 15 ohms given a base R measurement of 15 ohms. N6LF found that for a 90 deg monopole the method of summing resistances c; /archives//html/Topband/2012-09/msg00309.html (10,556 bytes)
117. Topband: 1810 kHz signal (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Wed, 3 Oct 2012 07:57:47 -0600; If someone here could take a map and plot all of the the data points, the area from which the signal originates will become clear. Then someone can travel to that area and do some local direction fin; /archives//html/Topband/2012-10/msg00138.html (7,389 bytes)
118. Re: Topband: Monopole Elev Pattern w.r.t. Earth Conductivity (score: 1): Author: "telegrapher9@gmail.com" <telegrapher9@gmail.com>; Date: Wed, 24 Oct 2012 09:56:56 -0600; For DX we are interested in elevation angles from 3-15 degrees. How much error is there in a NEC model of a monopole at these elevations? Dave WX7G Sent from my Verizon Wireless 4GLTE smartphone I ha; /archives//html/Topband/2012-10/msg00291.html (11,848 bytes)
119. Re: Topband: [Topband] Antenna analysers in close proximity to BC station (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Sat, 3 Nov 2012 09:22:56 -0600; One way to confirm that it is the BC station is to test the antenna during the day then at night when the (most) BC stations reduce(s) power. You might even be able to take a valid measurement when t; /archives//html/Topband/2012-11/msg00036.html (7,367 bytes)
120. Re: Topband: Toroidal common mode choke (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Sat, 17 Nov 2012 12:25:28 -0700; Bill, the G3TXQ website has the balun info you seek. _______________________________________________ Topband reflector - topband@contesting.com; /archives//html/Topband/2012-11/msg00275.html (8,177 bytes)

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