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321. Re: [RFI] I. C. E. products question (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 31 Dec 2007 09:42:50 -0800
I'm a member of NCCC, the Northern California Contest Club. A question was recently asked on our reflector about the merits of various BPF filter sets. ICE RF bandpass filters are fairly well regarde
/archives//html/RFI/2007-12/msg00070.html (7,487 bytes)

322. Re: [RFI] I. C. E. products question (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 31 Dec 2007 13:11:24 -0800
Not quite -- the sample of NCCC members on the reflector do. And our comments are on the RF bandpass filters, NOT the power filters. Danny, K6MHE, just sent me some very disturbing comments about wha
/archives//html/RFI/2007-12/msg00074.html (8,377 bytes)

323. Re: [RFI] RF quiet wired routers (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 31 Dec 2007 18:24:18 -0800
Not a bad cable, a bad router. The cable is acting like a long wire antenna because the router has lousy common mode isolation on the output that the cable is connected to. The simple ferrite chokes
/archives//html/RFI/2007-12/msg00080.html (7,683 bytes)

324. Re: [RFI] RF quiet wired routers (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 31 Dec 2007 22:48:16 -0800
VERY interesting. I'd guess that the cable was miswired on both ends, with the transmission circuits improperly split between twisted pairs of the CAT5. Such a cable would pass a simple continuity te
/archives//html/RFI/2008-01/msg00001.html (6,825 bytes)

325. Re: [RFI] Wired vs Wireless Routers for RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 09 Jan 2008 13:48:18 -0800
This is a well known issue. See http://audiosystemsgroup.com/RFI-Ham.pdf 73, Jim Brown K9YC _______________________________________________ RFI mailing list RFI@contesting.com http://lists.contesting
/archives//html/RFI/2008-01/msg00015.html (8,495 bytes)

326. Re: [RFI] Wired vs Wireless Routers for RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 11 Jan 2008 06:30:47 -0800
Exactly how and where did you connect the shields on each end? What equipment (makes/models) were you connecting? The biggest problem with using shielded CAT5 for this purpose is that for much of the
/archives//html/RFI/2008-01/msg00025.html (8,280 bytes)

327. Re: [RFI] Wired vs Wireless Routers for RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 12 Jan 2008 08:09:41 -0800
cable First, you MUST use enough turns before you begin seeing much benefit from these chokes. The particular cores you purchased may be too small for this use. I recommend the 2.4-inch o.d. 1.4-inch
/archives//html/RFI/2008-01/msg00034.html (10,514 bytes)

328. Re: [RFI] Wired vs Wireless Routers for RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 12 Jan 2008 08:18:49 -0800
In general, shielded ("screened" in British English) Ethernet cable is standard in Europe, whereas unshielded CAT5 is standard in North America. Thus, the Ethernet equipment and connectors you descri
/archives//html/RFI/2008-01/msg00035.html (9,817 bytes)

329. Re: [RFI] Wired vs Wireless Routers for RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 12 Jan 2008 08:22:24 -0800
Thanks, Don. To clarify -- are you saying that the female Ethernet connectors built into the cable modem, the router, and the computers all have shield contacts? Where did you buy these cables? Did y
/archives//html/RFI/2008-01/msg00036.html (9,298 bytes)

330. Re: [RFI] TV RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 26 Jan 2008 16:38:52 -0800
That's a VERY broad statement. Exactly WHAT is the problem? Pix? Audio? How is the TV set fed? Is it connected to an audio system or video system? As K1TTT noted, a likely cause is a pin 1 problem in
/archives//html/RFI/2008-01/msg00058.html (7,099 bytes)

331. Re: [RFI] TV RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 28 Jan 2008 16:36:43 -0800
Well, sort of. But ANY antenna that is WORKING is going to put RF in your house. A better way to look at it is to say that some antenna SYSTEMS inherently put more RF there than others. :) The word "
/archives//html/RFI/2008-01/msg00065.html (10,858 bytes)

332. Re: [RFI] TV RFI - an update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 12 Feb 2008 20:28:28 -0800
You may be right, but I doubt it. In other words, it's far more likely to be common mode current lighting up a pin 1 problem. If the transmit frequency is 28 MHz or 50 MHz (unlikely nowadays), changi
/archives//html/RFI/2008-02/msg00014.html (7,736 bytes)

333. Re: [RFI] TV RFI - an update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 13 Feb 2008 07:35:34 -0800
Yes. This is quite good advice. A major problem with both MATV and CATV systems is leakage caused by lousy connections. 73, Jim K9YC _______________________________________________ RFI mailing list R
/archives//html/RFI/2008-02/msg00016.html (7,582 bytes)

334. Re: [RFI] TV RFI - an update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 13 Feb 2008 12:15:36 -0800
The most common path for HF RF into a VCR is common mode current on the antennna leadin coupling via a "pin 1 problem" in the VCR. This is especially true on the lower HF bands. Study the section in
/archives//html/RFI/2008-02/msg00020.html (8,373 bytes)

335. Re: [RFI] TV RFI - an update 2 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 13 Feb 2008 20:28:48 -0800
The chassis and circuit common of the VCR and TV have capacity coupling to the power system ground via the power transformer (and bypass capacitors), even if they have no green wire ground. So pin 1
/archives//html/RFI/2008-02/msg00022.html (8,967 bytes)

336. Re: [RFI] TV RFI - an update 2 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 14 Feb 2008 09:58:04 -0800
As long as all turns are in the same direction, clock wise or counter clock wise doesn't matter. Iron vs. ferrite DOES make a difference. I haven't measured or seen data for any multiturn powdered ir
/archives//html/RFI/2008-02/msg00024.html (8,507 bytes)

337. Re: [RFI] TV RFI - an update 2 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 14 Feb 2008 21:01:34 -0800
There is MEASURED data on my website for 1-14 turn chokes wound with #18 wire on 2.4" toroids in #31, #43, #61, #77, and #78. There is also MEASURED data for coaxial chokes on #31 cores. http://audio
/archives//html/RFI/2008-02/msg00036.html (7,285 bytes)

338. Re: [RFI] 2 Wire 2701 HG (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 23 Feb 2008 13:51:57 -0800
As long as the electronics wants 5VDC to run, it doesn't much matter whether that 5V comes from the el cheapo noise generator or a much better one. You could, for example, simply use a 6V filament tr
/archives//html/RFI/2008-02/msg00050.html (7,418 bytes)

339. Re: [RFI] impulsive RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 03 Mar 2008 10:30:15 -0800
Jim's point about directional properties of antennas away from their design frequencies is well taken. Another hint, learned from Fox Hunting, is that an HT with a duck can be form a directional ante
/archives//html/RFI/2008-03/msg00007.html (6,999 bytes)

340. Re: [RFI] Modem PS noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 05 Mar 2008 09:42:49 -0800
And I'll emphasize two VERY important phrases in Dale's preceding sentence, that he clearly understands but didn't articulate in detail -- "in the correct places" and "good board layout techniques."
/archives//html/RFI/2008-03/msg00012.html (7,863 bytes)

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