Hi Grant and Todd I suggest there is also potential for a 4th problem - mutual coupling between the vertical wire and supporting tree. Any such coupling would be smaller for the 43 ft vertical if it was located further away from the tree.
It would be interesting to see if there is any noticeable change in the SWR curve and performance by increasing the distance between the vertical wire and tree trunk. But I also appreciate that space and other factors may preclude Todd from doing this. 73, Brian VK3MI Message: 11 Date: Sat, 29 Dec 2018 09:00:03 -0800 From: Grant Saviers <[email protected]> To: Todd Goins <[email protected]>, TopBand List <[email protected]> Subject: Re: Topband: Inverted L improvement question - Part 2 Message-ID: <[email protected]> Content-Type: text/plain; charset=utf-8; format=flowed Problem #1. The swr indicates about a 140Khz plus < 2:1 bandwidth (2 * 1880-1810) which implies a high radial resistance. Are the elevated radials fully insulated from trees, not contacting foliage, etc? Add three more. Problem #2. Your coiled coax choke may be making things worse. Check out the just released designs from K9YC and build one. 17 turns RG400 on one FT240-31. Problem #3. The increased gain of the T may be causing BCB desense of the 7300. You need a BCB filter. Also the poor choke may be letting a lot of common mode noise into the antenna. Grant KZ1W _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
