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Total 45 documents matching your query.

21. Re: Topband: Detuning shunt fed tower and noise from a TV (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Sun, 05 Oct 2008 20:02:10 -0400
Hi Paul, I have successfully detuned 3 different towers using the same approach (detuning loop with variable capacitor) as you. In my situation the 160m transmit antenna has some other nearby towers
/archives//html/Topband/2008-10/msg00034.html (8,694 bytes)

22. Re: Topband: Light fiber question (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Thu, 24 Oct 2013 21:36:47 -0400
There are niche applications, called "antenna remoting", where photonic and fiberoptic technologies are used to transmit RF signals from an antenna to a remote receiver. You can buy commercial system
/archives//html/Topband/2013-10/msg00226.html (8,701 bytes)

23. Re: Topband: Chasing Shaclelton (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Wed, 08 Jan 2014 20:41:19 -0500
I have studied quite a bit of the history of polar exploration and I don't think there is any correlation between solar activity and the launching of polar expeditions. Multiple expeditions were unde
/archives//html/Topband/2014-01/msg00084.html (8,327 bytes)

24. Re: Topband: Using 80m 1/4 vertical on 160 (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Mon, 02 Jun 2014 21:07:39 -0400
Hi Mike, I have a dual-band 160/80 meter vertical system that is based on 1/4-wave verticals on 80. I switch in loading coils to make them work on 160. The 160 capability was added as an afterthought
/archives//html/Topband/2014-06/msg00009.html (8,632 bytes)

25. Re: Topband: Signal source (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Tue, 25 Nov 2014 08:09:27 -0500
Antenna analyzers such as the AEA or MFJ put out tunable low power CW signals that can be used for this purpose. My AEA VIA Bravo has a "CW source" mode that generates a very stable signal. I've used
/archives//html/Topband/2014-11/msg00129.html (7,636 bytes)

26. Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Sun, 07 Dec 2014 19:49:54 -0500
It peaks at a heading of about 75 degrees from eastern MA, as best as I can determine on a Hi-Z 8 circle array. I made a video of its spectrum as captured on my Elecraft P3 and posted it on YouTube:
/archives//html/Topband/2014-12/msg00113.html (8,538 bytes)

27. Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Mon, 08 Dec 2014 21:09:22 -0500
Same estimated heading (~75 deg) from the Boston area and same as last night. The relatively big signal strength suggests something in NA rather than EU. But that would place it almost out a sea from
/archives//html/Topband/2014-12/msg00139.html (10,076 bytes)

28. Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Tue, 09 Dec 2014 07:24:16 -0500
It is still coming in after my SR (1200Z) but dropping in strength. Given the hour, it is definitely not coming from EU. The origins are in NA. 73, John W1FV _________________ Topband Reflector Archi
/archives//html/Topband/2014-12/msg00151.html (9,470 bytes)

29. Re: Topband: That 1.9 MHz radar signal... (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Tue, 09 Dec 2014 19:22:27 -0500
narrowed it down to something in the Maine/New Brunswick.Nova Scotia areas. I would also put Newfoundland in the region of interest. From my location in the greater Boston area, the direction of arr
/archives//html/Topband/2014-12/msg00199.html (8,206 bytes)

30. Re: Topband: That 1.9 MHz radar signal... (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Tue, 09 Dec 2014 19:55:54 -0500
I'm not hearing it either at 0054Z. This transmitter appears to go on and off, so we can't deduce much unless we know it's on. Joe (VO1NA), do you have a directional RX antenna? If so, your readings
/archives//html/Topband/2014-12/msg00204.html (8,301 bytes)

31. Re: Topband: 8 circle: DXE vs Hi-Z (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Tue, 16 Dec 2014 20:50:33 -0500
A few comments based on my own experience with various receiving arrays: Circle diameter of the Hi-Z array: A circle diameter of 200 feet is specified for the Hi-Z 8-circle array on 160m. In fact, I
/archives//html/Topband/2014-12/msg00275.html (12,127 bytes)

32. Re: Topband: 8 circle: DXE vs Hi-Z (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Wed, 17 Dec 2014 20:58:55 -0500
Good points about polarization. If the signals and/or noise are polarized predominantly in one state, then RDF may not be a good predictor of SNR performance, particularly if the antenna receives pre
/archives//html/Topband/2014-12/msg00279.html (10,716 bytes)

33. Re: Topband: Non-resonant receive antennas (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Thu, 18 Dec 2014 20:43:10 -0500
A few years ago, I put up a low, non-resonant dipole, about 150 feet long and 10 feet high for use as an auxiliary receiving antenna on 160. My main receiving antenna was and still is an array of sho
/archives//html/Topband/2014-12/msg00311.html (11,238 bytes)

34. Re: Topband: Non-resonant receive antennas (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Fri, 19 Dec 2014 19:58:00 -0500
My low dipole is broadside NE-SW but at only 10 feet high, it is essentially omnidirectional in azimuth and a cloud-warmer in elevation. The instances where I've seen the dipole provide a receiving a
/archives//html/Topband/2014-12/msg00340.html (11,969 bytes)

35. Re: Topband: Preamplifiers (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Mon, 02 Feb 2015 18:16:22 -0500
I have used the RPA-1 and various Clifton Laboratories units (although not specifically the Z10043). Both are excellent. I have not tried a KD9SV preamp. I particularly like the Clifton Laboratories
/archives//html/Topband/2015-02/msg00015.html (8,315 bytes)

36. Re: Topband: Foreign stns using NA remotes for K1N (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Wed, 04 Feb 2015 21:08:26 -0500
<W8JI>: The last good DXCC's were when we had a mileage limit. Even then, Just for the record, it is true that W1BB had two stations, but they were in the same town (Winthrop, MA) and literally minut
/archives//html/Topband/2015-02/msg00127.html (9,205 bytes)

37. Re: Topband: Point Shirley (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Sat, 28 Feb 2015 14:04:48 -0500
W1BB's water tower shack was in a little hut at the base of the tower. I visited Stew back in the 1970's and got a tour of that QTH. As I recall, the shack also served as a civil defense facility, wh
/archives//html/Topband/2015-02/msg00774.html (7,743 bytes)

38. Re: Topband: K1FK to JA Via 160-Meter Long Path (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Thu, 24 Sep 2015 19:06:35 -0400
I just wanted to add another data point to this subject. I have heard LP JA's on 160 on several occasions from my location in FN42 (eastern MA), anywhere from 2120Z to 2200Z in December and January,
/archives//html/Topband/2015-09/msg00109.html (7,795 bytes)

39. Re: Topband: 9 circle array (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Mon, 07 Dec 2015 20:33:38 -0500
Hello TopBanders, I am the author of the original NCJ article, published in September/October and November/December issues, which is the basis for the YCCC/DX Engineering RX array. I also collaborate
/archives//html/Topband/2015-12/msg00112.html (9,435 bytes)

40. Re: Topband: 9 circle array (score: 1)
Author: "John Kaufmann" <jkaufmann@alum.mit.edu>
Date: Tue, 08 Dec 2015 07:16:41 -0500
In general, any metal in the near field of the array will have an effect on pattern. This includes radials under the array. It's hard to predict what the results will be in a particular situation, bu
/archives//html/Topband/2015-12/msg00116.html (9,072 bytes)


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