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Total 45 documents matching your query.

21. Re: Topband: 160m noise (score: 1)
Author: "Tom Rauch" <w8ji@contesting.com>
Date: Wed, 10 Nov 2004 11:23:51 -0500
Jeff, First remember the number order is sometimes random, a higher number does not always reflect higher permeability. When soft iron materials are made larger than a certain physical thickness and
/archives//html/Topband/2004-11/msg00063.html (10,245 bytes)

22. RE: Topband: 160m noise (score: 1)
Author: "Jeff Maass" <jmaass@columbus.rr.com>
Date: Wed, 10 Nov 2004 12:07:08 -0500
I appreciate the education from you and from Jim (and I'm eagerly awaiting his promised article!) I'd missed the shifting of the impedance peak downward in multi-turn suppression apps. I'd looked at
/archives//html/Topband/2004-11/msg00064.html (11,713 bytes)

23. Re: Topband: 160m noise (score: 1)
Author: "Tom Rauch" <w8ji@contesting.com>
Date: Wed, 10 Nov 2004 13:48:18 -0500
been a big disapointment for me. I have NEVER had a snap on type of core make any difference on any frequency. One piece cores sometimes help, but it takes a dozen or more to raise the impedance eno
/archives//html/Topband/2004-11/msg00065.html (9,588 bytes)

24. Re: Topband: 160m noise (score: 1)
Author: "Tom Rauch" <w8ji@contesting.com>
Date: Wed, 10 Nov 2004 13:49:54 -0500
cores. It's too complex to answer without writing an article Jeff. 73 Tom _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mail
/archives//html/Topband/2004-11/msg00066.html (8,987 bytes)

25. 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)

26. RE: Topband: 160m noise (score: 1)
Author: "Jeff Maass" <jmaass@columbus.rr.com>
Date: Wed, 10 Nov 2004 16:21:05 -0500
This has been a very interesting, and somewhat frustrating, discussion! My applications are: 2) Reducing the effect of the feedline on the effectiveness of a Beverage or pennant/flag antenna. From T
/archives//html/Topband/2004-11/msg00068.html (11,788 bytes)

27. Re: Topband: 160m noise (score: 1)
Author: W2pm@aol.com
Date: Wed, 10 Nov 2004 16:21:43 EST
In my noisy New Joisy QTH Ive found acres are not necessary and a 100 ft move away from the noise makes a BIG improvement on 160 and doubly so at VHF - my wireless router has crap all over 2meters an
/archives//html/Topband/2004-11/msg00069.html (8,095 bytes)

28. RE: Topband: 160m noise (score: 1)
Author: Larry Molitor <w7iuv@yahoo.com>
Date: Wed, 10 Nov 2004 14:21:29 -0800 (PST)
Jeff, Here is my experiences with feedline common mode problems. Others may have different experiences/opinions. Your mileage may vary! I have yet to find an instance where a feedline choke of any de
/archives//html/Topband/2004-11/msg00070.html (10,599 bytes)

29. Topband: 160m noise (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Wed, 10 Nov 2004 16:43:15 -0800
Just by chance, I happened to be designing a common mode choke for my generator over the weekend. I had a couple of FT-240-43 cores in my junkbox. Five turns gives about 490 ohms |Z| at 3.5 MHz (abou
/archives//html/Topband/2004-11/msg00072.html (10,428 bytes)

30. Re: Topband: 160m noise (score: 1)
Author: Sinisa Hristov <shristov@ptt.yu>
Date: Wed, 10 Nov 2004 20:03:11 -0500
Although it's a good idea to dissipate the incident RF power, a choke can be very effective if designed with parallel resonance at RF frequency. Series impedance will be very high (many tens of kOhms
/archives//html/Topband/2004-11/msg00073.html (10,092 bytes)

31. Re: Topband: 160m noise (score: 1)
Author: Sinisa Hristov <shristov@ptt.yu>
Date: Wed, 10 Nov 2004 20:03:47 -0500
With high imepdance antennas one needs much better chokes than with 50-Ohm antennas. I would recommend winding RG174 (or even smaller coax) on FT240-43. You must wind enough turns to position the par
/archives//html/Topband/2004-11/msg00074.html (8,529 bytes)

32. Re: Topband: 160m noise (score: 1)
Author: "Tom Rauch" <w8ji@contesting.com>
Date: Wed, 10 Nov 2004 20:47:23 -0500
choke turns Jeff, Amidon, being a distributor, makes up their own numbers. That part looks like it might be a Fair-rite 5977003801, which is a 2.4 od x1.4 id x .5 thick core. I'm not sure if that co
/archives//html/Topband/2004-11/msg00075.html (9,850 bytes)

33. RE: Topband: 160m noise (score: 1)
Author: "Jeff Maass" <jmaass@columbus.rr.com>
Date: Wed, 10 Nov 2004 22:06:49 -0500
Tom: That seems likely - same dimensions, same material. I've gotta tell you, Amidon's numbering scheme seems to make more semblance of sense. Actually *describing* the item in some way that doesn't
/archives//html/Topband/2004-11/msg00076.html (11,851 bytes)

34. Re: Topband: 160m noise (score: 1)
Author: Pete Smith <n4zr@contesting.com>
Date: Thu, 11 Nov 2004 06:20:13 -0500
The common-mode choke arrangement described by ON4UN in his Low-Band DXing book (Third Edition, Fig. 7-19 and the text in section 9.2 on pages 7-18/19) seems to meet Tom's specification -- high serie
/archives//html/Topband/2004-11/msg00078.html (10,439 bytes)

35. Re: Topband: 160m noise (score: 1)
Author: "Tom Rauch" <w8ji@contesting.com>
Date: Thu, 11 Nov 2004 07:51:27 -0500
his Low-Band DXing on pages impedance and As long as the grounds on the input and output are not common with each other (if two are used) or the equipment!! _________________________________________
/archives//html/Topband/2004-11/msg00080.html (8,700 bytes)

36. Re: Topband: 160m noise (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Thu, 11 Nov 2004 05:59:26 -0800
Yeah, I tried a B&W line filter here for my generator problem. It had two very impressive looking 2" toroid inductors in series with each leg of the AC line and shunt caps in between (5 section LPF).
/archives//html/Topband/2004-11/msg00081.html (9,199 bytes)

37. Re: Topband: 160m noise (score: 1)
Author: Ronald Gorski <R.Gorski@Astronautics.com>
Date: Thu, 11 Nov 2004 08:45:12 -0600
The most effective method, that I have tried, for minimizing common mode current on coax braid is to wind the coax in a single layer solenoid of sufficient inductance such that a common size variable
/archives//html/Topband/2004-11/msg00083.html (10,732 bytes)

38. Re: Topband: 160m noise (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sat, 13 Nov 2004 19:15:34 -0800
Jeff, I found an FT-240-77 wrapped around the power cord of my R4C (long story). In any case, I took it off and measured it with a Network Analyzer and then dumped the data to M-S Excel: http://www.d
/archives//html/Topband/2004-11/msg00145.html (10,846 bytes)

39. 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)

40. Re: Topband: 160m noise (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sun, 14 Nov 2004 08:48:32 -0800
For convenience, Jeff, I just used a piece of stranded insulated wire (I think it was #16). The impedance you get a low frequencies should be the same regardless of the wire size (within reason). At
/archives//html/Topband/2004-11/msg00152.html (10,599 bytes)

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