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101. Re: [TowerTalk] Radial Ends Buried (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Fri, 18 Nov 2022 12:28:51 -0700; That appears to be an excellent and useful article, but as an engineer I was taught never to specify dimensions and measures to such impractical and irrelevant resolution. Spec'ing radial lengths to; /archives//html/Towertalk/2022-11/msg00117.html (7,959 bytes)
102. Re: [TowerTalk] Prosistel 61D (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Sun, 25 Dec 2022 11:56:44 -0700; I don't see how it would be the shear pin, though, if your antenna is rotating back and forth like you said. Even a free spinning worm gear should not allow the toothed gear to move ... at least not; /archives//html/Towertalk/2022-12/msg00169.html (13,858 bytes)
103. Re: [TowerTalk] Prosistel 61D (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Mon, 26 Dec 2022 09:58:57 -0700; Some of that really isn't true. The earlier AC model of the rotator was called just PST61, while the later DC model (with better water protection) is called the PST61D. Prosistel clearly describes; /archives//html/Towertalk/2022-12/msg00177.html (11,089 bytes)
104. Re: [TowerTalk] TIC plastic gears (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Fri, 6 Jan 2023 10:38:14 -0700; I've 3D printed knobs using 1/4" brass inserts with a set screw for the shaft. The inserts are knurled on the outside and you use a soldering iron to get them hot enough to press into the shaft hole; /archives//html/Towertalk/2023-01/msg00027.html (10,449 bytes)
105. Re: [TowerTalk] Trylon (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Sun, 15 Jan 2023 14:51:48 -0700; I asked ChatGPT the question: "how can I calculate the wind pressure in Pascals if I know the wind speed and surface area?" It returned: "Wind pressure can be calculated using the formula: P = 0.613; /archives//html/Towertalk/2023-01/msg00048.html (8,648 bytes)
106. [TowerTalk] DIY Air Wound Coils (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Tue, 17 Jan 2023 00:13:46 -0700; If you have access to a 3D printer, or access to somebody who has a 3D printer, here is an easy way to make your own air wound coils like the old Air-Dux coils. The video is pretty clumsy, but you s; /archives//html/Towertalk/2023-01/msg00050.html (7,473 bytes)
107. Re: [TowerTalk] DIY Air Wound Coils (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 18 Jan 2023 20:31:04 -0700; This should definitely be feasible. My example was really basic ... just a cylindrical hole with a rectangular slot on top of it that only infringes on about 40% of the cylindrical hole. The remain; /archives//html/Towertalk/2023-01/msg00065.html (9,295 bytes)
108. Re: [TowerTalk] DIY Air Wound Coils (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 18 Jan 2023 21:30:37 -0700; I could add another four slots in the form for a total of eight. You wouldn't need to use them all on smaller coils, and if you used them all on larger coils it would be easy to just turn over whiche; /archives//html/Towertalk/2023-01/msg00067.html (12,548 bytes)
109. [TowerTalk] Fwd: DIY Air Wound Coils (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Thu, 19 Jan 2023 11:31:32 -0700; Wes seems to be having trouble posting to the reflector, so he asked me to forward this post. 73, Dave AB7E Hi Dave, For some reason my messages to the reflector are bouncing. Even my message to t; /archives//html/Towertalk/2023-01/msg00072.html (8,064 bytes)
110. Re: [TowerTalk] Tower Collapse in South Dakota (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Sat, 21 Jan 2023 10:43:24 -0700; I think ham radio tower installations have far too unpredictable potential failure modes to make generalizations. Many are short enough to be relatively stiff and would tend to lay down in the case; /archives//html/Towertalk/2023-01/msg00085.html (9,253 bytes)
111. Re: [TowerTalk] Common Mode Choke Locations (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Thu, 26 Jan 2023 19:28:57 -0700; I'm not trying to promote choke overkill, but look at it this way. If it is a truly high impedance CMC at the antenna, the shield of the remaining coax run to the shack is essentially a receiving ant; /archives//html/Towertalk/2023-01/msg00113.html (9,060 bytes)
112. [TowerTalk] Another DIY Air Wound Coil Form (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Fri, 27 Jan 2023 19:25:03 -0700; I recently posted a link to a method of using a 3D printed form to make an air wound coil like the old Air-Dux coils and I still think that's the most efficient way to do it, but that version results; /archives//html/Towertalk/2023-01/msg00123.html (8,463 bytes)
113. Re: [TowerTalk] DIY Air Wound Coils (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Sat, 28 Jan 2023 11:16:57 -0700; Are you asking if my OpenSCAD code pulls variable information from Brian's excellent COIL program? If so, the answer is that it doesn't. You can get what you want from Brian's program and then load; /archives//html/Towertalk/2023-01/msg00125.html (10,992 bytes)
114. Re: [TowerTalk] More Radials = Higher SWR??? (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Sun, 5 Feb 2023 17:03:12 -0700; A full size vertical has a feed point impedance of 35 ohms give or take a couple. A compromise vertical like yours would be even less ... probably 25 ohms or less. When you don't use the radials yo; /archives//html/Towertalk/2023-02/msg00014.html (15,561 bytes)
115. Re: [TowerTalk] More Radials = Higher SWR??? (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 8 Feb 2023 17:06:04 -0700; Per my previous post, I prefer the FA-VA5 as well ... and it is about half the cost of the Rig Expert. One of it's nice features is the 5-band SWR display for checking which coax lines go to which an; /archives//html/Towertalk/2023-02/msg00038.html (9,687 bytes)
116. Re: [TowerTalk] Force 12 C31XR Modeling (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 22 Feb 2023 10:50:01 -0700; If you use a razor blade to make a shallow slit in the Romex directly over the ground wire, you can just pull the ground wire out without significantly affecting the insulation. If you do that on a; /archives//html/Towertalk/2023-02/msg00122.html (10,265 bytes)
117. Re: [TowerTalk] AFCI RFI? (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Thu, 16 Mar 2023 10:50:02 -0700; Yes, I believe that the issue is more one of susceptibility to RFI rather than the breakers being the cause of RFI. And yes, EATON certainly did have a problem, to the point they were replacing brea; /archives//html/Towertalk/2023-03/msg00019.html (9,320 bytes)
118. Re: [TowerTalk] P3020-V1-CW360 - Hall sensor (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Sun, 19 Mar 2023 14:18:57 -0700; Very interesting! That looks like a very elegant approach. I am trying to do something similar because I don't want to have to replace the linear potentiometer in my PST-71D, except that I am planni; /archives//html/Towertalk/2023-03/msg00050.html (10,797 bytes)
119. Re: [TowerTalk] ChatGPT (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 5 Apr 2023 14:56:46 -0700; ChatGPT is often a quicker way to get an answer to a question than for example, doing a search on Google. But that's because ChatGPT can simply pull stuff out of its database for the answer and come; /archives//html/Towertalk/2023-04/msg00014.html (10,379 bytes)
120. Re: [TowerTalk] ChatGPT (score: 1): Author: David Gilbert <ab7echo@gmail.com>; Date: Wed, 5 Apr 2023 16:31:37 -0700; Yup. 73, Dave AB7E It's probably useful to recall what the "GPT" in ChatGPT stands for -- Generative Pretrained Transformer; GPTs are a particularly effective form of long-term memory that's useful; /archives//html/Towertalk/2023-04/msg00016.html (8,990 bytes)

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