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21. RE: Topband: PSK-31 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 27 Apr 2004 16:20:56 -0500
As the old saying goes, "it depends." In this case, it depends on where the sound card clips/distorts, how much RF you might have floating around your shack, and providing immunity to hum/buzz that m
/archives//html/Topband/2004-04/msg00237.html (8,604 bytes)

22. RE: Topband: PSK-31 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 27 Apr 2004 23:17:45 -0500
Your point is well taken. I just looked at the output of the computer running full gain from the PSK software. The third harmonic (the strongest spur) is 24 dB below the fundamental. Not hard clippin
/archives//html/Topband/2004-04/msg00246.html (9,981 bytes)

23. RE: Topband: PSK-31 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 28 Apr 2004 22:59:44 -0500
That's -3 dB. Huh? how does 50% power turn into -10 dB? According to my math it's -3 dB. BTW, I measured the relative gain of the slider on my sound card. The first notch down from the top is 3 dB be
/archives//html/Topband/2004-04/msg00257.html (9,848 bytes)

24. RE: Topband: PSK-31 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 29 Apr 2004 10:36:08 -0500
Acceptable by what standard? -60 dB re: fundamental is 0.1% distortion. -45 dB (which I measured only 3 dB below max out) is 0.3%. In the communications world, those are very low numbers. If I can ea
/archives//html/Topband/2004-04/msg00260.html (13,981 bytes)

25. Re: Topband: RX Loops (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 17 May 2004 20:41:27 -0500
On Mon, 17 May 2004 13:59:21 -0700 (PDT), Rick Karlquist wrote: It does if the local noise is predominantly one or the other, and in a certain direction relative to the station you are trying to hear
/archives//html/Topband/2004-05/msg00041.html (7,016 bytes)

26. RE: Topband: RX Loops (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 18 May 2004 07:12:07 -0500
If you live in the country, with no power lines, no utilities, and no cable, that is certainly true. But it is definitely NOT if you live in the city. My lot is 150' x 40'. On 160 meters, there are a
/archives//html/Topband/2004-05/msg00045.html (7,724 bytes)

27. [TowerTalk] Interesting New DX Engineering Product (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 26 Jul 2004 00:02:01 -0500
One of the guys in our local ham club came back from Dayton with a very interesting new product from DX Engineering. As soon as he showed it to me, I called up DX Engineering and bought two of them.
/archives//html/Topband/2004-07/msg00055.html (8,008 bytes)

28. Re: Topband: two wires Beverage (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 27 Jul 2004 09:49:12 -0500
When you're thinking about the impedance, remember that this is the impedance of that line when used as a twisted pair transmission line. That will NOT be the impedance of a Beverage antenna that you
/archives//html/Topband/2004-07/msg00063.html (8,012 bytes)

29. Re: Topband: Deep QSB (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 11 Oct 2004 09:19:08 -0500
I think short calls are ALWAYS a good idea. If I'm responding to a call, I like to simply put in my call sign once if I think the other guy should hear me well, twice if probably not, pause, then kee
/archives//html/Topband/2004-10/msg00046.html (7,359 bytes)

30. Re: Topband: 160m noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 09 Nov 2004 00:15:09 -0600
Simple physics -- you cause RF current to flow in a wire, and it WILL radiate. You may CALL it a ground wire, but Mother Nature knows that it is an antenna. Yes, these beasts are well known as HF noi
/archives//html/Topband/2004-11/msg00046.html (10,320 bytes)

31. RE: Topband: 160m noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 10 Nov 2004 08:19:05 -0600
No, it's not "sloppy," it's an advanced application of the physics of how ferrites work, and a method of getting very effective suppression from commonly available components. The 20-300 MHz recommen
/archives//html/Topband/2004-11/msg00060.html (9,891 bytes)

32. RE: Topband: 160m noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 10 Nov 2004 15:01:39 -0600
I've measured up to 10 turns, and used up to 14 turns. In research for an EMC paper published by the Audio Engineering Society, I wound 14 turns of a mic cable around the #43 toroid to reduce the shi
/archives//html/Topband/2004-11/msg00067.html (10,512 bytes)

33. Re: Topband: RFI cure kit (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 11 Nov 2004 09:52:35 -0600
I'll address what I've spent a lot of time studying -- common mode radiation from various computer and Ethernet sources. You might ask this question over on the RFI list, where guys like Dale, WA9ENA
/archives//html/Topband/2004-11/msg00085.html (9,915 bytes)

34. Re: Topband: 160m noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 14 Nov 2004 09:33:47 -0600
Remembering that for suppression, we want R to be large and X to be small at the frequency of the interfering signal, it would be quite helpful to see data for R and X separately. Thanks for posting
/archives//html/Topband/2004-11/msg00150.html (8,933 bytes)

35. Re: Topband: BCS Clone 80m trap problem (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 14 Nov 2004 09:19:49 -0600
Are there commercially available traps for wire antennas built according to your design recommendations? Any that are KW-rated? If so, which ones (specific mfrs/models)? This question has immediate s
/archives//html/Topband/2004-11/msg00151.html (8,373 bytes)

36. Re: Topband: 160m noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 14 Nov 2004 11:10:00 -0600
Of course -- IF the interfering signal is only at a single frequency, and if you have time to tune each and every choke to each and every line. Rarely do the stars line up that way. My ham station op
/archives//html/Topband/2004-11/msg00153.html (10,582 bytes)

37. Re: Topband: 160m noise (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 14 Nov 2004 13:17:07 -0600
The point is that it is almost never necessary to do so if you can maximize the suppression that can be achieved without resonance, as well as the trouble you can get into when you DO achieve series
/archives//html/Topband/2004-11/msg00155.html (9,618 bytes)

38. Re: Topband: High pass Filters (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 24 Nov 2004 17:13:23 -0600
ICE (in Indianapolis) makes decent high pass filters with a cutoff just below 1.8 MHz. I have two of them, one of which is in line with my rig all the time. It works quite well. I've also measured it
/archives//html/Topband/2004-11/msg00230.html (7,998 bytes)

39. Re: Topband: Yaesu Key clicks (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 28 Nov 2004 15:46:33 -0600
example I tried working 160 this weekend to scare up some multipliers for CQWW, and found it next to dead. I was able to make a grand total of 4 QSO's with a KW. Yes, I heard a few guys trying to wor
/archives//html/Topband/2004-11/msg00245.html (8,181 bytes)

40. Re: Topband: High pass Filters (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 28 Nov 2004 15:47:56 -0600
Their filters look good on their website. Have you seen measured data? Jim K9YC _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com
/archives//html/Topband/2004-11/msg00246.html (8,283 bytes)

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