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Total 10 documents matching your query.

1. Topband: electrically shortening a tall grounded tower (score: 1): Author: Bob Kupps <n6bk@yahoo.com>; Date: Fri, 25 Sep 2009 20:50:17 -0700 (PDT); Hi Is there any effective way to electrically shorten a tall grounded tower to 1/4 wave? I tried modeling a 1/4 wave cage surrounding the tower but it still shows a lot of current in the protruding s; /archives//html/Topband/2009-09/msg00116.html (7,047 bytes)
2. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: W2XJ <w2xj@nyc.rr.com>; Date: Sat, 26 Sep 2009 00:56:37 -0400; What software are you using? Often modeling software can not handle cages. _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mail; /archives//html/Topband/2009-09/msg00117.html (9,032 bytes)
3. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: Bob Kupps <n6bk@yahoo.com>; Date: Fri, 25 Sep 2009 22:10:47 -0700 (PDT); EZNEC 5. Regardless of my inability to model I would be interested in any practical solutions that have already been tried and known to work. Thanks 73Bob What software are you using? Often modeling; /archives//html/Topband/2009-09/msg00118.html (9,561 bytes)
4. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: W2XJ <w2xj@nyc.rr.com>; Date: Sat, 26 Sep 2009 01:22:40 -0400; I have EZNEC5 and it delivers large errors with cages. a _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mailman/listinfo/topba; /archives//html/Topband/2009-09/msg00119.html (10,353 bytes)
5. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: "Robin" <wb6tza@socal.rr.com>; Date: Fri, 25 Sep 2009 22:55:02 -0700; I operated for a number of years with a 250 ft tower with sloper 1/4 wave lines attached 1/4 wave from the top of the tower. I simply hooked coax between the tower and the sloper like you would feed; /archives//html/Topband/2009-09/msg00120.html (10,955 bytes)
6. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: Herbert Schoenbohm <herbs@vitelcom.net>; Date: Sat, 26 Sep 2009 08:34:47 -0400; You might consider feeding it with a shunt fed cage at about 1/4 down from the top and attach elevated 1/4 wave radials at that point. I had a 308 foot tower and took the easy way out by running up a; /archives//html/Topband/2009-09/msg00123.html (9,079 bytes)
7. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: k3bu@optimum.net; Date: Sat, 26 Sep 2009 14:13:42 +0000 (GMT); How tall is the tower? There are actually benefits of having taller than 1/4 wave, up to about 1/2 wave. One way to "insulate" the tower portion is to use the "trombones" - hairpin stub with capacito; /archives//html/Topband/2009-09/msg00125.html (9,233 bytes)
8. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Sun, 27 Sep 2009 08:58:51 -0600; Bob, rather than using a series hi-Z (trap) to decouple the upper portion of the tower a low-Z shunt element can be used. At the 130' point a loaded 'radial' sysatem of sorts is attached. An example; /archives//html/Topband/2009-09/msg00142.html (9,452 bytes)
9. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: w2xj <w2xj@nyc.rr.com>; Date: Sun, 27 Sep 2009 11:05:51 -0400; 1/4 wave stubs do work. They are frequently used in broadcast work. The problem is with the modeling. You really need a professional (expesnive) program preferrably employing NEC 4. This is one of th; /archives//html/Topband/2009-09/msg00143.html (10,872 bytes)
10. Re: Topband: electrically shortening a tall grounded tower (score: 1): Author: DAVID CUTHBERT <telegrapher9@gmail.com>; Date: Sun, 27 Sep 2009 11:24:46 -0600; Bob, the base of the tower needs to be ungrounded. The tower can be fed at the base via a parallel LC or it can be fed at the junction of the tower and the decoupling wires or tubes. The disadvantage; /archives//html/Topband/2009-09/msg00146.html (11,083 bytes)

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