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381. Re: [RFI] Coaxial Choke (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 15 Apr 2009 09:24:44 -0700
I am sure, and I'm become an authority on the subject by doing a lot of scientific work on the topic and publishing it. Gee -- since when is science defined by what one reads on email lists? What hap
/archives//html/RFI/2009-04/msg00048.html (8,759 bytes)

382. Re: [RFI] Coaxial Choke (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 15 Apr 2009 12:57:18 -0700
One of the working principles of scientific discovery is that those who discover a scientific principle get to name it, and it was Neil Muncy, an exham who works in pro audio who figured it out, it h
/archives//html/RFI/2009-04/msg00050.html (9,964 bytes)

383. Re: [RFI] Coaxial Choke (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 16 Apr 2009 07:40:06 -0700
Strongly agree, on all counts. all aspects of EMC really draw on a thorough understanding of the fundamentals and their application to the systems involved. As Roger observed, the skills of a general
/archives//html/RFI/2009-04/msg00055.html (7,793 bytes)

384. Re: [RFI] Coaxial Choke (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 19 Apr 2009 23:43:23 -0700
How many of them has designed an ANTENNA with anything approaching the percentage bandwidth of an audio system? And how many decades passed before HP produced an RF generator or analyzer that covered
/archives//html/RFI/2009-04/msg00061.html (8,393 bytes)

385. Re: [RFI] Coaxial Choke (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 20 Apr 2009 09:56:58 -0700
Agreed. My point in the original post is that RF guys (and video guys) often discount the complexity of audio. 73, Jim K9YC _______________________________________________ RFI mailing list RFI@contes
/archives//html/RFI/2009-04/msg00063.html (7,881 bytes)

386. Re: [RFI] where to buy FairRite? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 27 Apr 2009 15:14:13 -0700
Yes, these are the best parts I know of for HF chokes. Note that these parts are NOT suitable for use as transformers -- too much loss -- but they are ideal for common mode chokes. If not what ferrit
/archives//html/RFI/2009-04/msg00068.html (8,666 bytes)

387. Re: [RFI] where to buy FairRite? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 27 Apr 2009 18:02:38 -0700
My apologies if I insulted an honest man. My common mode choke designs are pretty conservative, but I have no meaningful way of testing them at greater than 1.5kW. The only way that I've been able to
/archives//html/RFI/2009-04/msg00075.html (8,609 bytes)

388. [RFI] Fwd: EMC Seminar by Henry Ott June 2-3 in NJ (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 04 May 2009 09:34:26 -0700
If you can find the time to do it, Henry's seminars are excellent. I attended a 3-day version about five years ago in Palo Alto. One of Henry's greatest strengths is that he develops clear explanatio
/archives//html/RFI/2009-05/msg00000.html (6,988 bytes)

389. Re: [RFI] Fairrite at Dayon? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 05 May 2009 09:43:38 -0700
There will almost certainly be Fair-Rite products for sale, but most will be at exhorbitant prices. Jay at Array Solutions has recently begun stocking some Fair-Rite cores to use in his choke and bal
/archives//html/RFI/2009-05/msg00002.html (7,453 bytes)

390. Re: [RFI] Fairrite at Dayon? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 05 May 2009 16:08:44 -0700
-- Hi Doc, The info is far to limited to tell you much. At a minimum, the seller should tell you the mfr, the material (mix), and the part number so that you can tie them to a data sheet. If you can'
/archives//html/RFI/2009-05/msg00004.html (7,620 bytes)

391. Re: [RFI] Alarm Systems and EMI/EMC (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 09 May 2009 19:52:32 -0700
No experience with these guys, but security systems are notorious for RFI susceptibility. FWIW -- that 300 MHz range is commonly used for garage doors and remote control of A/V systems. I don't know
/archives//html/RFI/2009-05/msg00010.html (7,172 bytes)

392. Re: [RFI] Alarm Systems and EMI/EMC (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 10 May 2009 08:06:51 -0700
No surprise there -- the RF up there is in the same spectrum as the control systems. OTOH, I don't recall anything comparable in downtown Chicago, where all the broadcasters are on two buildings only
/archives//html/RFI/2009-05/msg00022.html (9,145 bytes)

393. Re: [RFI] Alarm Systems and EMI/EMC (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 10 May 2009 08:23:44 -0700
Good morning Mike, Strongly agree. But as KB4T observes, they can also suffer from poor design. Another example. Many of us have converted our Ethernet installations to use 802.11b (WiFi). These syst
/archives//html/RFI/2009-05/msg00023.html (8,898 bytes)

394. Re: [RFI] CATV Leakage? Horizonal Osc Harmonics (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 11 May 2009 09:57:51 -0700
Yes. The picture carrier of an analog TV signal on cable channel 18 is 145.25 MHz. There are three principal mechanisms by which the carriers Larry is hearing are radiated. 1) Directly by the TV set'
/archives//html/RFI/2009-05/msg00029.html (8,366 bytes)

395. Re: [RFI] [Amps] 4C65 low loss ferrite - BIG toroids (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 11 May 2009 10:15:20 -0700
I just compared the data sheet for this material with Fair-Rite #61. The two materials are quite similar, but 4C65 looks to be superior, to the extent that it maintains a low loss tangent to about 20
/archives//html/RFI/2009-05/msg00030.html (7,229 bytes)

396. Re: [RFI] Mast-mount TV Pre-Amp -- Avoiding RFI & Overload? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 04 Jun 2009 08:42:00 -0700
I would also use one or more common mode chokes near the preamp to prevent fundamental overload by VHF and HF transmitters that could excite the downlead as a long wire antenna. Use the guidelines i
/archives//html/RFI/2009-06/msg00009.html (9,066 bytes)

397. Re: [RFI] Latest RFI-proof SUVs (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 10 Jun 2009 22:32:50 -0700
Highlander? Honda Pilot? Subaru 4 cylinder Forester or Outback? My experience with a Toyota Sequoia (BIG SUV) was very bad from an RFI perspective. Mounted a hamstick on the luggage rack, with coax b
/archives//html/RFI/2009-06/msg00025.html (8,772 bytes)

398. Re: [RFI] Latest RFI-proof SUVs (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 11 Jun 2009 08:31:17 -0700
That's great news, Doug. Where/how do you get power for the radio? Any filtering or decoupling on the power? Where is the coax shield connected on the antenna end? Is the radio chassis connected to a
/archives//html/RFI/2009-06/msg00029.html (8,344 bytes)

399. Re: [RFI] Latest RFI-proof SUVs (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 11 Jun 2009 17:03:06 -0700
So perhaps the problems I had are now a thing of the past! That would be good news. Thanks for all the detail. I did not attempt to use the vehicle chassis to carry DC, in large part because I had gr
/archives//html/RFI/2009-06/msg00031.html (8,858 bytes)

400. Re: [RFI] TVI filters (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 29 Jun 2009 10:03:34 -0700
Yes, those are exactly the right questions to ask. It is VERY unlikely that you need a filter. Depending on how RFI is getting into the system, you probably DO need one or more good common mode choke
/archives//html/RFI/2009-06/msg00066.html (7,577 bytes)

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