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Total 1348 documents matching your query.

81. Topband: Gamma matching crank-up tower (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Thu, 24 Oct 2002 19:54:43 -0400
When cables are passed down through the tower center, the tower forms a less-than-perfect Faraday cage and the cables are not excited nearly as much as when hanging on the outside. Bad luck also mig
/archives//html/Topband/2002-10/msg00136.html (8,369 bytes)

82. Topband: Large TSTM areas as MF "wall" (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Tue, 29 Oct 2002 11:19:21 -0500
All of the data I have seen shows the effect rapidly dimiminishes as the frequency moves below upper VHF and is immeasurable at HF and lower. The only noticeable effect of weather is in noise (from
/archives//html/Topband/2002-10/msg00153.html (7,416 bytes)

83. Topband: 160 Propagation & Weather (score: 1)
Author: w8ji@contesting.com (Tom Rauch)
Date: Tue, 29 Oct 2002 20:00:17 -0500
I can't imagine anyone trying to measure such tiny changes without extensive ground systems and very accurate and stable FS meters on a ground wave path. Sky wave would be worse yet, especially with
/archives//html/Topband/2002-10/msg00160.html (7,626 bytes)

84. Topband: Source of terminator resistors for EWE's? (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Thu, 31 Oct 2002 13:35:25 -0500
With a EWE antenna or any other small-area antenna of that family like Flags, Pennants, or small verticals almost any style resistor except wire-wound will work. If it is near a transmitting antenna,
/archives//html/Topband/2002-10/msg00172.html (8,655 bytes)

85. Topband: CQ 160 2003 Rules Changes - Limit Mulit-ops to 30 or 36 hours (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Mon, 30 Sep 2002 22:19:28 -0400
Time for a reality check on contests everyone!! No matter what we do, rules will never be "fair". For example, the Stew can be won from any thousand-mile radius densely populated area of amateurs by
/archives//html/Topband/2002-09/msg00003.html (8,092 bytes)

86. Topband: chicken wire ground screen (reply) (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 4 Sep 2002 00:11:08 -0400
Disconnecting or connecting a wire makes no difference at all, as long as you have sufficient wire in the ground. If you have an inadequate radial ground, the interaction is quite complex and very u
/archives//html/Topband/2002-09/msg00028.html (9,385 bytes)

87. Topband: Linear loaded whip versus base /center loading verticals / shorted Inv L (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 4 Sep 2002 00:11:06 -0400
Actually a linear loaded antenna (assuming a helical wire the whole length) has about the same radiation resistance as somewhere between base and center loading. It ranks in somewhere that area for
/archives//html/Topband/2002-09/msg00030.html (8,093 bytes)

88. Topband: Displacement currents (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 4 Sep 2002 08:51:11 -0400
Displacement currents are fictitious currents that were "created" or invented to explain how current flowing into one lead of a capacitor manages to flow out of the other lead, without charges actua
/archives//html/Topband/2002-09/msg00033.html (7,958 bytes)

89. Topband: Displacement currents (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 4 Sep 2002 22:56:10 -0400
Hi Dave, My point is the only way to reduce loss with a vertical near earth is to provide a conductive path for the currents back to the antenna area as evenly as possible over a large area that exte
/archives//html/Topband/2002-09/msg00037.html (7,494 bytes)

90. Topband: Linear loaded whip versus base /center loading verticals / shorted Inv L (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 4 Sep 2002 22:56:09 -0400
We certainly have some vague or nebulous definitions in common use Earl!! Even if we are talking about linear loading as a folded section or hairpin, and not a continuously wound linear-loaded verti
/archives//html/Topband/2002-09/msg00038.html (8,331 bytes)

91. Topband: Re: MIG wire: Source for radial wire? (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Fri, 6 Sep 2002 18:35:56 -0400
The very thin porous overlay on standard MIG wire will disappear in any condition when exposed to moisture, even if the wire is suspended in air. I have to watch how extra wire reels for my MIG weld
/archives//html/Topband/2002-09/msg00059.html (7,997 bytes)

92. Topband: Radials (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Sun, 8 Sep 2002 15:35:35 -0400
I've never seen any measured data (where the correct parameters were measured) that indicated wire size is important to radial loss. The primary reason size is not important is easy to see, if we lo
/archives//html/Topband/2002-09/msg00073.html (9,430 bytes)

93. Topband: Flag Transformer (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 11 Sep 2002 07:44:44 -0400
What does the "Faraday shield" connect to Mike? Does the coax shield float from ground at the antenna? 73, Tom W8JI W8JI@contesting.com
/archives//html/Topband/2002-09/msg00110.html (6,886 bytes)

94. Topband: Coupling between bev and other antennas (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 11 Sep 2002 07:44:43 -0400
The 775DSP has control system timing problems that generate thumps and bumps when on CW split, as well as severe leading-edge power overshoot in the PA. None of that is good on the PA transistors, o
/archives//html/Topband/2002-09/msg00111.html (8,531 bytes)

95. Topband: front end protection (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 11 Sep 2002 07:44:41 -0400
You have to be *very careful* when adding relays in the TX path. It is a major headache that almost anyone who has sold products in aftermarket accessory manufacturing knows all too well. The RX ant
/archives//html/Topband/2002-09/msg00112.html (9,050 bytes)

96. Topband: Coupling of bev to tx system (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 11 Sep 2002 09:33:16 -0400
While it is true that disconnecting a 1/4 wl vertical from anything else will reduce re-radiation substantially, the noise test described above can not prove anything in many (or most) cases. It is
/archives//html/Topband/2002-09/msg00118.html (8,115 bytes)

97. Topband: Flag Xfmr Measurements (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Wed, 11 Sep 2002 20:38:38 -0400
Bob, What measurement frequency does the LCIIB meter use in operation? It is an absolute requirement when making measurements of RF components such as transformers, inductors, and small value capaci
/archives//html/Topband/2002-09/msg00119.html (7,581 bytes)

98. Topband: Re: Back-to-Back Diodes (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Thu, 12 Sep 2002 20:11:00 -0400
Good point by Ward. It certainly can be a problem. Power detectors or clamps in RF switched devices can even cause RFI and TVI. For example, the TR switching diodes in some imported VHF amplifier ac
/archives//html/Topband/2002-09/msg00122.html (7,235 bytes)

99. Topband: Flag Xfmr Measurements (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Fri, 13 Sep 2002 21:52:08 -0400
I'm not saying anything one way or another about this because I haven't followed the discussion that close, but there is something to keep in mind. Transformers and matching systems with loss are no
/archives//html/Topband/2002-09/msg00126.html (7,578 bytes)

100. Topband: Vertical Antenna Feedpoint Above Ground - Part Deux (score: 1)
Author: W8JI@contesting.com (Tom Rauch)
Date: Mon, 16 Sep 2002 14:45:05 -0400
Every practical system will excite some small current on the outside of the shield anyway no matter how the connection is made, because the ground system is always less than perfect and the feedline
/archives//html/Topband/2002-09/msg00135.html (8,303 bytes)


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