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321. Re: Topband: RFI (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Tue, 30 Dec 2008 23:38:58 -0800; meter QRO from a Yaesu control cable? The RF on the cable's wires is not good for the control box! See the "Choke Cookbook" in http://audiosystemsgroup.com/RFI-Ham.pdf Which toroid size, quantity, an; /archives//html/Topband/2008-12/msg00301.html (7,154 bytes)
322. Re: Topband: Binocular transformer design (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Sun, 04 Jan 2009 20:08:05 -0800; Ferrite chokes are VERY difficult to measure with reasonable accuracy. Some of the difficulties and a couple of good measurement methods are described in the tutorials on my website. The principal re; /archives//html/Topband/2009-01/msg00027.html (8,584 bytes)
323. Re: Topband: Improving the Fabulous CQ 160 Contest (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Tue, 06 Jan 2009 21:29:44 -0800; Yes. Yes, but don't scale it -- the Stew Perry scale is quite good! Dump multipliers. That's the major element that gives so great an advantage to those in the most populous areas. Besides -- who lik; /archives//html/Topband/2009-01/msg00037.html (7,769 bytes)
324. Re: Topband: Spiderbeam pole (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Fri, 09 Jan 2009 09:10:43 -0800; The literature is pretty clear on this, and NEC is pretty good at doing the math. The goal of the top loading is to get the ELECTRICAL length close to a quarter wave. Essentially the top loading can; /archives//html/Topband/2009-01/msg00072.html (8,547 bytes)
325. Re: Topband: Inverted L (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Mon, 12 Jan 2009 13:06:35 -0800; system or if an elevated counterpoise would work better. Google to find N6LF's website and study it. 73, Jim K9YC _______________________________________________ Topband mailing list Topband@contesti; /archives//html/Topband/2009-01/msg00107.html (6,710 bytes)
326. Re: Topband: 160 Meter Propagation (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Tue, 13 Jan 2009 10:26:10 -0800; Barry, Count me among those who consider comparison of one antenna to the other by switching between them over and over again (or in diversity mode) and comparing voltmeter readings on many contacts; /archives//html/Topband/2009-01/msg00120.html (9,019 bytes)
327. Re: Topband: K9AY-Loop ? (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Tue, 13 Jan 2009 20:25:11 -0800; I agree the CHOKE is critical, and it should be brute force (that is, a design goal of 5Kohms at frequencies of interest). I do NOT agree that the ground is needed beyond for whatever it takes to mak; /archives//html/Topband/2009-01/msg00125.html (7,482 bytes)
328. Re: Topband: K9AY-Loop ? (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Wed, 14 Jan 2009 09:17:40 -0800; YES. YES. ANY wire will act as an antenna in the presence of excitation, depending on its length and the frequency. I like to think of chokes in wires like this as the equivalent of an egg insulator; /archives//html/Topband/2009-01/msg00128.html (11,622 bytes)
329. Re: Topband: K9AY-Loop ? (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Wed, 14 Jan 2009 13:47:49 -0800; The bead may make you feel better, but that's all its doing. It takes a resistive impedance on the order of 1K to do anything useful, which requires a lot of TURNS through a lossy ferrite! The bigges; /archives//html/Topband/2009-01/msg00129.html (7,959 bytes)
330. Re: Topband: K9AY-Loop ? (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Wed, 14 Jan 2009 13:57:18 -0800; Yes, looking for resonances with a dipper or equivalent is certainly a good idea. And it's quite helpful to do your listening for noise with a portable radio that you can tune to a frequency where yo; /archives//html/Topband/2009-01/msg00130.html (8,490 bytes)
331. Re: Topband: K9AY-Loop ? (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Thu, 15 Jan 2009 01:10:05 -0800; Yeah, it scares off elephants too. Proof -- you aren't troubled by elephants, so it must work. If you still believe that it works, I suggest that draw a circuit diagram with values, showing that ther; /archives//html/Topband/2009-01/msg00138.html (8,346 bytes)
332. Re: Topband: CQ 160 weird ideas (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Fri, 16 Jan 2009 11:43:41 -0800; I strongly agree, and I won't work a station who is working split mode in a contest EXCEPT when there are national frequency allocation issues that require the split (like 40M SSB). VP6DX was working; /archives//html/Topband/2009-01/msg00157.html (8,961 bytes)
333. Re: [TowerTalk] Topband: Slant (Shunt) Feeding 88' Tower on 160 (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Sat, 17 Jan 2009 12:09:07 -0800; ALL of your questions are answered quite well in the ON4UN book, and it includes MANY other useful ideas. Buy it and study it! The ARRL Antenna Book also includes lots of useful information and ideas; /archives//html/Topband/2009-01/msg00171.html (7,237 bytes)
334. Re: Topband: Recycled ferrites for 160m (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Wed, 21 Jan 2009 09:38:51 -0800; YES. One VERY important caution. Antenna analyzers typically have stray input capacitance on the order of 10 pF! The equivalent circuit of a ferrite choke is a parallel equivalent circuit, and for mo; /archives//html/Topband/2009-01/msg00216.html (8,914 bytes)
335. Re: Topband: Recycled ferrites for 160m (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Wed, 21 Jan 2009 15:30:04 -0800; EXACTLY! There's nothing "magic" about 50 ohms -- it's simply a value that we often get for free built into our spectrum analyzer voltmeter. We could improve accuracy at lower values of unknown Z by; /archives//html/Topband/2009-01/msg00221.html (8,405 bytes)
336. Re: Topband: 160 to NA (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Sat, 24 Jan 2009 13:59:37 -0800; YES! Over a period of several hours, I called a bunch of EU and SA stations who were CQing endlessly and well above my noise level. Some were answering callers fairly often, but many were not. I simp; /archives//html/Topband/2009-01/msg00247.html (8,359 bytes)
337. Re: Topband: 160 to NA (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Sun, 25 Jan 2009 21:27:28 -0800; I don't agree. In any 160 contest, there are big signals wall to wall, especially in the JA window between 1810 and 1825, and those of use with decent radios and RX antennas manage to hear quite well; /archives//html/Topband/2009-01/msg00279.html (9,243 bytes)
338. Re: Topband: locals (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Tue, 27 Jan 2009 15:17:17 -0800; I've owned and loved a pair of TS850s and a pair of FT1000MPs, but happily replaced all but one of the MPs to buy a pair of K3s. Other members of our club (NCCC) have done the same. I have three neig; /archives//html/Topband/2009-01/msg00301.html (8,988 bytes)
339. Re: Topband: RG-6 Coax (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Wed, 28 Jan 2009 17:55:58 -0800; Yes. It's VERY important to realize that RG numbers are so generic as to be meaningless. Any major cable mfr builds several dozen RG59s and a dozen or so RG6s. There are MANY differences -- jacket, d; /archives//html/Topband/2009-01/msg00314.html (8,341 bytes)
340. Re: Topband: Home Depot RG-6 Cable (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Thu, 29 Jan 2009 13:39:52 -0800; Much of that resistance is the shield, which is typically Al foil and a light braid. It's always a good idea to study data sheets for coax, and to buy only major brands that publish good data sheets.; /archives//html/Topband/2009-01/msg00319.html (7,588 bytes)

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