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Total 9 documents matching your query.

1. Topband: Shunt feed question (score: 1): Author: Marty Ray <dxcc1@comcast.net>; Date: Mon, 14 Oct 2019 19:44:38 -0400; I am shunt feeding a 70 ft Trylon tower with a Tennadyne T12.10-30HD LPDA at 70 ft and a full size 40m rotatable dipole at 79 ft, (the top of the mast is ~85 ft). Both antennas have relays that elect; /archives//html/Topband/2019-10/msg00119.html (6,806 bytes)
2. Re: Topband: Shunt feed question (score: 1): Author: Herbert Schoenbohm <herbert.schoenbohm@gmail.com>; Date: Tue, 15 Oct 2019 16:19:09 -0300; Best to use a 3 or 4 wire cage feed and you will find the match easier. You should tap the tower at 50 feet and work down till you find the sweet spot. A 500 to 750 vac variable will take care of any; /archives//html/Topband/2019-10/msg00121.html (8,583 bytes)
3. Re: Topband: Shunt feed question (score: 1): Author: Marty Ray <dxcc1@comcast.net>; Date: Tue, 15 Oct 2019 16:30:59 -0400; Thanks for the response Herb. I can obtain a good match using the 65 ft tap point, but my question is why my analyzer is measuring a change in the feedpoint resistance (real component of R + jX). Reg; /archives//html/Topband/2019-10/msg00123.html (9,086 bytes)
4. Re: Topband: Shunt feed question (score: 1): Author: Wes <wes_n7ws@triconet.org>; Date: Tue, 15 Oct 2019 12:44:45 -0700; Try a series capacitor. Wes N7WS I have tried two shunt tap points, one at 65 feet and another at 45 feet. Using a Rig Expert AA-55 Zoom, the Rs measured a little over 100 ohms on the 65 foot versio; /archives//html/Topband/2019-10/msg00125.html (8,150 bytes)
5. Re: Topband: Shunt feed question (score: 1): Author: Gene Smar via Topband <topband@contesting.com>; Date: Wed, 16 Oct 2019 10:06:55 -0400; Marty: Did you mean it literally when you wrote you added the shunt capacitor, that is, did you put the cap from the shunt wire/coax center conductor junction to ground? The cap in a "shunt-feed" arr; /archives//html/Topband/2019-10/msg00127.html (9,491 bytes)
6. Re: Topband: Shunt feed question (score: 1): Author: N4ZR <n4zr@comcast.net>; Date: Wed, 16 Oct 2019 11:55:18 -0400; FWIW, I had a shunt feed on my 97-foot Rohn 25 with stacked tribanders and a shorty forty on it. I spent a long time trying to find a 50-ohm tap point on the tower and was never successful, so I chan; /archives//html/Topband/2019-10/msg00129.html (10,057 bytes)
7. Re: Topband: Shunt feed question (score: 1): Author: Lee STRAHAN <k7tjr@msn.com>; Date: Wed, 16 Oct 2019 17:00:49 +0000; Marty, You may be seeing errors in your readings due to broadcast pickup. This is common when modern R+Jx measurement tools are connected to large antenna structures. Others have described ways aroun; /archives//html/Topband/2019-10/msg00132.html (9,836 bytes)
8. Re: Topband: Shunt feed question (score: 1): Author: "Joe Subich, W4TV" <lists@subich.com>; Date: Wed, 16 Oct 2019 16:46:12 -0400; Because the *shunt* capacitor creates an L network with the impedance (R +/- jX) at the bottom of the gamma arm. Mathematically you are doing a series to parallel conversion. For normal gamma operati; /archives//html/Topband/2019-10/msg00133.html (10,930 bytes)
9. Re: Topband: Shunt feed question (score: 1): Author: Wes <wes_n7ws@triconet.org>; Date: Wed, 16 Oct 2019 15:22:27 -0700; Because you're using a shunt capacitor. This in conjunction with the inductive reactance forms an L-network. As I said before, you need a series capacitor. Move the tap to get 50 +jX and then add -; /archives//html/Topband/2019-10/msg00135.html (10,192 bytes)

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