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141. Re: [TowerTalk] antenna feed line (kind of on topic) (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 26 Apr 2005 23:37:01 -0500
No comment on the impedance. But while you're thinking about this, remember that mismatch contributes relatively little additional loss to the total picture until there's a LOT of mismatch. See the A
/archives//html/Towertalk/2005-04/msg00730.html (7,726 bytes)

142. [TowerTalk] Cellular Base Station Power Levels (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 12 May 2005 10:40:30 -0500
For an "RFI for audio guys" applications note I am writing, I would like to know the approximate transmit power levels for cellular base stations. I'm guessing around 100w ERP on peaks? Jim Brown K9Y
/archives//html/Towertalk/2005-05/msg00269.html (6,927 bytes)

143. Re: [TowerTalk] NEAR FIELD RADIATION (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 12 May 2005 17:36:12 -0500
No problem -- you simply need to fix or put bandaids on the pin 1 problems in your equipment. You will also need to be equally serious with the home entertainment stuff. My city lot antenna farm is a
/archives//html/Towertalk/2005-05/msg00291.html (7,591 bytes)

144. Re: [TowerTalk] Serious RF Problem (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 12 May 2005 22:03:17 -0500
I know you guys are tired of hearing it, but the answer is pin 1 problems in the ham gear and computers we use to the control the ham gear. Now, choking stuff, as Brett describes, can help that. But
/archives//html/Towertalk/2005-05/msg00307.html (8,073 bytes)

145. Re: [TowerTalk] Serious RF Problem (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 13 May 2005 06:08:30 -0500
Sadly, it is not odd -- the ham radio community, and the engineers who design for it, are mostly unaware of it. When Neil Muncy (ex-W3WJE) taught us about it in 1994, virtually ALL pro audio equipmen
/archives//html/Towertalk/2005-05/msg00322.html (10,547 bytes)

146. Re: [TowerTalk] "Thief" (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 17 May 2005 00:25:52 -0500
IMO, if a seller chooses to "advertise" via this list, someone who is seriously agrieved and has exhausted reasonable recourse directly with the seller is entirely in line to post here. The post to w
/archives//html/Towertalk/2005-05/msg00471.html (9,212 bytes)

147. [TowerTalk] Al Kahn, K4FW, Silent Key (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 16 Jun 2005 11:46:32 -0500
Reprinted from the North Shore Radio Club EMail List. Jim Brown = = = = = = = = = = K4FW, Albert R. Kahn, passed away on June 15th. Al started Ten-Tec after being bored with retired life. He was also
/archives//html/Towertalk/2005-06/msg00415.html (8,320 bytes)

148. [TowerTalk] VHF/UHF Switches (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 19 Jun 2005 12:31:32 -0500
I would like to find a 1x4 antenna switches that are usable at 220 MHz and 440 MHz. Is such an animal even practical? Jim K9YC _______________________________________________ See: http://www.mscomput
/archives//html/Towertalk/2005-06/msg00458.html (6,597 bytes)

149. Re: [TowerTalk] wires in trees (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 28 Jun 2005 11:23:50 -0500
I am a huge fan of fan dipoles -- parallel wires connected to the same center insulator/balun. On FD, we use a fan that covers 80 and 40, and others that cover 20/15/10. Each are full size half waves
/archives//html/Towertalk/2005-06/msg00639.html (8,366 bytes)

150. Re: [TowerTalk] rugged 6 meter beam ? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 05 Jul 2005 21:36:22 -0500
ESPECIALLY after it has gone through tropo or the ionosphere -- it is well known that many propagation mechanisms cause the polarization to be modified. K9YC _________________________________________
/archives//html/Towertalk/2005-07/msg00108.html (9,671 bytes)

151. Re: [TowerTalk] Rigging Dipoles and Growing Old (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 07 Jul 2005 13:38:01 -0500
Since the coax is running perpendicular to the antenna, its proximity to the tower seems unlikely to be much of an electrical issue, especially if you have a good balun at the feedpoint. The other is
/archives//html/Towertalk/2005-07/msg00144.html (8,237 bytes)

152. Re: [TowerTalk] Fields and coax (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 24 Jul 2005 10:20:40 -0500
Yes. BUT: Below radio frequencies, a cable "shield" provides magnetic field rejection NOT by shielding (because it is far too thin in terms of skin depth to provide shielding), but by virtue of the p
/archives//html/Towertalk/2005-07/msg00663.html (10,441 bytes)

153. Re: [TowerTalk] Fields and coax (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 24 Jul 2005 11:27:52 -0500
What do you mean by "perfect?" Perfect means that there would be no external field, perfect uniformity of shield current around the circumference of the shield, no "holes" in the shield, and implies
/archives//html/Towertalk/2005-07/msg00669.html (7,858 bytes)

154. Re: [TowerTalk] perfect braid... (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 24 Jul 2005 21:13:17 -0500
I strongly agree that shield leakage should be quite minimal with the cable you described. And much of that common mode stuff with AM broadcast may be pin 1 problems. Jim ____________________________
/archives//html/Towertalk/2005-07/msg00708.html (7,731 bytes)

155. [TowerTalk] Lubricant for Struthers SWR Bridge (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 30 Jul 2005 10:23:48 -0500
I bought a Struthers bridge at Dayton. It's the type where there are slugs for each frequency range, and each slug is switchable between power levels. One slug works fine, but the switches in the oth
/archives//html/Towertalk/2005-07/msg00835.html (7,331 bytes)

156. Re: [TowerTalk] Sparky Pays a Visit (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 01 Aug 2005 20:30:56 -0500
Somehow, I missed the part where you said that the ground rods were all bussed together outside the house, that the power system ground was tied into that ground outside the house, etc. There can be
/archives//html/Towertalk/2005-08/msg00013.html (7,698 bytes)

157. [TowerTalk] City of Chicago Towers (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 02 Aug 2005 10:54:20 -0500
I'm starting to think seriously about putting something small (the smallest StepIR) on a tower in my Chicago backyard. Can anyone provide info on current regulations and their interpretation? I'm in
/archives//html/Towertalk/2005-08/msg00028.html (6,759 bytes)

158. Re: [TowerTalk] Sparky Pays a Visit (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 03 Aug 2005 11:24:24 -0500
You are missing the point. MOV's get fried from an accumulation of spikes that they dissipate. When they fry, they may short, or they may open, and they can even catch fire! When MOV's are used in mo
/archives//html/Towertalk/2005-08/msg00050.html (9,131 bytes)

159. Re: [TowerTalk] Sparky Pays a Visit (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 03 Aug 2005 13:37:57 -0500
In some installations, concrete very LOW conductivitity is desired. Examples are electric railways and sidewalk heaters, where the concrete may serve as an insulator. Jim ____________________________
/archives//html/Towertalk/2005-08/msg00064.html (8,776 bytes)

160. Re: [TowerTalk] Sparky Pays a Visit (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 03 Aug 2005 13:40:07 -0500
YES! Jim _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
/archives//html/Towertalk/2005-08/msg00065.html (8,972 bytes)

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