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361. Re: [RFI] DSL Filter Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 07 Mar 2009 11:42:04 -0800
Roger, Exactly how was the response measured? What source and load impedances? 73, Jim K9YC _______________________________________________ RFI mailing list RFI@contesting.com http://lists.contesting
/archives//html/RFI/2009-03/msg00007.html (7,395 bytes)

362. Re: [RFI] DSL Filter Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 07 Mar 2009 13:38:41 -0800
Thanks Roger. The characteristic impedance of most paired cable, including audio cables and telephone cables, is on the order of 70-100 ohms. CAT5 is 100 ohms. 600 ohms has not been used in pro audio
/archives//html/RFI/2009-03/msg00010.html (11,066 bytes)

363. Re: [RFI] DSL Filter Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 08 Mar 2009 17:31:46 -0800
That's sort of the direction I was thinking about. Note that one can get quite serious with a common mode choke without affecting the differential mode circuit at all. Thanks for the info re: 2.2 MHz
/archives//html/RFI/2009-03/msg00017.html (8,447 bytes)

364. Re: [RFI] DSL Filter Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 08 Mar 2009 18:16:27 -0800
You're looking at the elephant through a differential-mode hole in the tent. Don't rule out the value of common-mode suppression, which is considerable. The KY and K-Com filters are both quite well t
/archives//html/RFI/2009-03/msg00019.html (8,554 bytes)

365. Re: [RFI] DSL Filter Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 09 Mar 2009 09:43:27 -0800
Many thanks, Chris. For those of us not working in the telco world, please translate DSLAM, CPE, and NID. :) Your point about RF entering the cable at one point and traveling along the cable for some
/archives//html/RFI/2009-03/msg00023.html (10,392 bytes)

366. Re: [RFI] DSL Filter Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 09 Mar 2009 13:10:54 -0800
OK. One can be really brute force with a common mode choke if it doesn't add capacitance across the line. You're looking at single turn data very different from what I see in the online catalog. It s
/archives//html/RFI/2009-03/msg00025.html (10,737 bytes)

367. [RFI] Telco Data Update (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 10 Mar 2009 17:36:13 -0800
I've added common mode data for the K-Com RF-2 Broadcast band filter. http://audiosystemsgroup.com/TelcoFilters.pdf This data confirms KI6KY's claim that his filters have signficantly more common mod
/archives//html/RFI/2009-03/msg00028.html (6,640 bytes)

368. Re: [RFI] 20 Meter Noise Level (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 Mar 2009 09:41:40 -0800
Sure -- you just proved it! Well, you already found one -- turn it off. :) There are two ways the noise is escaping from the TV. 1) The wires connected to it are acting as antennas and radiating it.
/archives//html/RFI/2009-03/msg00040.html (7,946 bytes)

369. Re: [RFI] 20 Meter Noise Level (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 Mar 2009 11:50:07 -0800
He said it was a projection TV. It's well known that many plasma sets generate bad RFI, but the advice I gave generically applies to any TV. That is, you can choke the wiring and kill the external an
/archives//html/RFI/2009-03/msg00044.html (8,140 bytes)

370. [RFI] Telco Filter Measurements (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 Mar 2009 11:57:07 -0800
Someone sent me a Radio Shack 2-line filter advertised as being effective on broadcast, CB, and ham RFI. I just measured it, and it is absolute garbage. It's a very high Q choke tuned to 7 MHz. It wo
/archives//html/RFI/2009-03/msg00045.html (7,148 bytes)

371. Re: [RFI] From CO8LY (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 Mar 2009 12:00:11 -0800
Eduardo, You have received lots of help and advice from your friends around the world. It is long past time for you to do your part by either putting your log on LOTW or finding a QSL manager who doe
/archives//html/RFI/2009-03/msg00046.html (7,776 bytes)

372. Re: [RFI] 160M incoming RFI (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 Mar 2009 12:48:59 -0800
I've been hearing something like this too, and so far don't have a clue. In my case, it seems to be several kHz wide, drifts around a bit, and comes and goes. I've mostly heard it between 1820 and 18
/archives//html/RFI/2009-03/msg00048.html (6,825 bytes)

373. Re: [RFI] Dimmer Switch Help (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 Mar 2009 17:36:25 -0800
FWIW, the so-called technical advice on the Lutron website is mostly a bunch of technomumbojumbo doubletalk, and your buddy redacted isn't much better. Since the dimmer mfrs refuse to make RF-quiet d
/archives//html/RFI/2009-03/msg00056.html (9,550 bytes)

374. [RFI] Fwd: EMC Seminar by Henry Ott Consultants, June 2-3, 2009 in New Jersey (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 24 Mar 2009 10:35:43 -0700
This is an announcement for an excellent tutorial seminar by Henry Ott, WA2IRQ. Henry is an very good teacher, and does these public seminars twice a year (once on the east coast, once on the west co
/archives//html/RFI/2009-03/msg00061.html (7,500 bytes)

375. Re: [RFI] 40 M and DirecTV (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 09 Apr 2009 09:04:39 -0700
Hi Rick, See suggestions below. 73, Jim K9YC I wouldn't suspect anything on the roof, other than possible rectification creating a UHF spur that is getting into the satellite. Pretty unlikely. Sympto
/archives//html/RFI/2009-04/msg00009.html (7,946 bytes)

376. Re: [RFI] update <was> 40m (and other) noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 11 Apr 2009 13:28:21 -0700
Of course not. No reason why it should. For 30M, a multiturn choke on #31 or #43 material is needed. Study http://audiosystemsgroup.com/RFI-Ham.pdf Over the past few months, I've been gradually addin
/archives//html/RFI/2009-04/msg00025.html (7,888 bytes)

377. Re: [RFI] update <was> 40m (and other) noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 11 Apr 2009 15:05:48 -0700
Note that I do NOT recommend MOV surge suppression products, which is what these devices are. MOVs can be really bad news on branch circuits, because they can actually CAUSE destructive failures of i
/archives//html/RFI/2009-04/msg00027.html (8,702 bytes)

378. Re: [RFI] update <was> 40m (and other) noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 12 Apr 2009 09:24:20 -0700
Eric, No one is throwing rocks at YOU, but at MOVs. They are VERY dangerous, for several reasons, all of which are documented on my website. Yes, they are widely used. Lots of people smoke tobacco, b
/archives//html/RFI/2009-04/msg00031.html (8,687 bytes)

379. Re: [RFI] DX Engineering Choke question... (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 14 Apr 2009 15:04:18 -0700
I'll be happy to measure and publish them if someone sends them to me. There is measured data the choking impedance of several high power DXE choke baluns on my website in the Power Point on Coaxial
/archives//html/RFI/2009-04/msg00039.html (8,858 bytes)

380. Re: [RFI] Coaxial Choke (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 14 Apr 2009 17:06:55 -0700
The material in the ARRL Handbook is woefully out of date and quite inadequate. See http://audiosystemsgroup.com/RFI-Ham.pdf for much more effective choke designs, with measured data to support them.
/archives//html/RFI/2009-04/msg00043.html (7,996 bytes)

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