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Total 302 documents matching your query.

81. Re: Topband: RX Loops - Some relevant facts (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Wed, 12 May 2004 15:04:01 -0700
sophomore. as electric 0 along in the within EMF I dunno, Eric. I just went to Tom's website and looked at his treatise on magnetic loops. http://www.w8ji.com/magnetic_receiving_loops.htm I can't fi
/archives//html/Topband/2004-05/msg00029.html (7,578 bytes)

82. Re: Topband: RX Loops (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Tue, 18 May 2004 18:13:43 -0700
Tom, While agree with the gist of what you are saying, there is one point where I am a little fuzzy. It has to do with reciprocity. The plot on your website (I think you attribute it to W7EL), shows
/archives//html/Topband/2004-05/msg00051.html (10,711 bytes)

83. Re: Topband: beverages: Diversity / Phasing (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sun, 23 May 2004 12:28:02 -0700
Just to add to what Ken has said, another key distinction between phased arrays and diversity systems is correlation. Phased arrays rely on combining correlated signal to increase the overall "clear
/archives//html/Topband/2004-05/msg00078.html (10,814 bytes)

84. Re: Topband: New way of DXing on Topband (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Mon, 21 Jun 2004 23:28:49 -0700
I recently got a QSL card from 3C0V for a 10 meter contact I never made. When I sent in for my QSL card the manager printed all the W4EF contacts in his log on the QSO label. I didn't even have the r
/archives//html/Topband/2004-06/msg00066.html (13,346 bytes)

85. Re: Re: Topband: Analog to Digital converter for 1.8MHz (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Fri, 2 Jul 2004 21:01:50 -0700
http://images.rfdesign.com/files/4/0599ANDERSON56.pdf Clearly specifying #bits isn't enough. Noise and non-linearities are a major consideration. The article does hint that very highdynamic range dig
/archives//html/Topband/2004-07/msg00014.html (9,958 bytes)

86. Topband: Fw: [dx-list] YV0 Closing Thursday ? ? ? (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Tue, 3 Aug 2004 14:11:13 -0700
FYI - if the YV0 guys do manage to get the 160 antennas up, looks its going to be a short window of opportunity. I guess Martti couldn't sweet talk the Venezuelan Navy into a longer stay. 73 de Mike,
/archives//html/Topband/2004-08/msg00006.html (7,223 bytes)

87. Re: Topband: K9AY Loop feeding? (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sun, 12 Sep 2004 23:34:48 -0700
Sure, Javier. The additional loss form the mismatch between the 50 ohm output of the matching tranformer at the K9AY loop and the 75 ohm RG-6 will be inconsequential. You could modify the matching tr
/archives//html/Topband/2004-09/msg00073.html (7,513 bytes)

88. Re: Topband: Tower insulator thickness? (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sat, 2 Oct 2004 22:20:00 -0700
Yeah, a 2 square foot x 7/16" thick fiberglass plate would be about 600pF of shunt capacitance to the concrete base. That amounts to about ~150 ohms shunt Xc at 1.8 MHz. If you cut out the center of
/archives//html/Topband/2004-10/msg00010.html (9,497 bytes)

89. Re: Topband: Angle of radiation to local stations? (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Thu, 14 Oct 2004 14:33:23 -0700
David, Arrange for your local friends to be on the air during the daytime (around local noon). At the time, you can be pretty much assured that absorption will be so high (at least at the current sol
/archives//html/Topband/2004-10/msg00071.html (9,527 bytes)

90. Re: Topband: TX9 will QRT Wednesday (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Tue, 19 Oct 2004 21:48:01 -0700
FYI, I heard them this evening on 17m SSB tell my neighbor N6DV that they would be on 80 meters at 1300 UT this morning (Wednesday). I am not sure, but I think they are sharing their Titanex V160 bet
/archives//html/Topband/2004-10/msg00098.html (7,605 bytes)

91. Topband: Vertical on the Beach? (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sun, 24 Oct 2004 22:51:13 -0700
I have been scouting some beachfront locations with a mind to do a portable operation on 160 meters and was wondering about "reflection zone" issues for saltwater enhancement. One of the locations I
/archives//html/Topband/2004-10/msg00132.html (7,377 bytes)

92. 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)

93. 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)

94. 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)

95. 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)

96. Re: Topband: High pass Filters (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Fri, 26 Nov 2004 19:02:54 -0800
below 1.8 It works meets its specs trash on 160 One caveat is that this filter has limited rejection (only 10 to 15dB) at the high end of the BC band: http://www.arraysolutions.com/Products/ice/filte
/archives//html/Topband/2004-11/msg00235.html (8,918 bytes)

97. Re: Topband: Yaesu Key clicks (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sat, 27 Nov 2004 16:06:01 -0800
Somebody should have asked that Yaesu rep why they sell CW filters if nobody uses them and how big contest stations can work 7000 qsos on CW if nobody is using that mode anymore. Sounds like that guy
/archives//html/Topband/2004-11/msg00239.html (7,974 bytes)

98. Topband: FT-240-77 Toroid Impedance R + jX Components (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sun, 26 Dec 2004 22:19:16 -0800
A while back I posted impedance vs frequency vs # of turns data for the Amidon FT-240-77 toroid (Fair-Rite Products P/N 5977003801). I have updated my website to include plots of the real (R) and ima
/archives//html/Topband/2004-12/msg00310.html (7,003 bytes)

99. Re: Topband: broadbanding an L (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Sun, 2 Jan 2005 13:23:53 -0800
I have an EZNEC/XZIZL model of an 80 meter dipole that will cover the entire 80 meter band (3.5 to 4.0 MHz) with a VSWR under 2.0:1 with very good efficiency. You do need a fixed LC network (challeng
/archives//html/Topband/2005-01/msg00016.html (9,198 bytes)

100. Re: Topband: FT-240-77 Toroid Impedance R + jX Components (score: 1)
Author: "Michael Tope" <W4EF@dellroy.com>
Date: Mon, 3 Jan 2005 15:23:30 -0800
If you look at the portion of the mu curves where u' is flat and much larger than u", that is where you expect the core to act like a high-mu low loss magnetic material. In that region the inductance
/archives//html/Topband/2005-01/msg00041.html (9,735 bytes)

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