{"id":181,"date":"2025-12-15T21:41:42","date_gmt":"2025-12-16T03:41:42","guid":{"rendered":"https:\/\/ka9kqh.net\/?p=181"},"modified":"2025-12-15T21:41:42","modified_gmt":"2025-12-16T03:41:42","slug":"t2lt-tuned-transmission-line-trap","status":"publish","type":"post","link":"https:\/\/ka9kqh.net\/?p=181","title":{"rendered":"T2LT (Tuned Transmission Line Trap)"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">What is it:<\/h2>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"435\" height=\"116\" src=\"https:\/\/ka9kqh.net\/wp-content\/uploads\/2025\/12\/t2lt-Tuned-Transmission-Line-Trap.jpg\" alt=\"\" class=\"wp-image-183\" style=\"aspect-ratio:3.7502164918695278;width:609px;height:auto\" srcset=\"https:\/\/ka9kqh.net\/wp-content\/uploads\/2025\/12\/t2lt-Tuned-Transmission-Line-Trap.jpg 435w, https:\/\/ka9kqh.net\/wp-content\/uploads\/2025\/12\/t2lt-Tuned-Transmission-Line-Trap-300x80.jpg 300w\" sizes=\"auto, (max-width: 435px) 100vw, 435px\" \/><figcaption class=\"wp-element-caption\">T2lt antenna diagram<\/figcaption><\/figure>\n<\/div>\n\n\n<p>The basic premise of the antenna is strip the 1\/4 wave of shield off the coax, leave a 1\/4 wave of coax with shield, and choke before the before the physical feed point.  <\/p>\n\n\n\n<p>This is resonant end-fed dipole, typically installed vertically.  There are lots of plans for this on the internet, but another &#8220;outside-the-box&#8221; ham and I were discussing it and had a few interesting ideas for this antenna for lower bands and how to potentially make it switchable between bands.  <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Using a length of coax long enough for a 1\/4 wave of the desired band plus feedline run with appropriate connectors on each end.<\/li>\n\n\n\n<li>Make a connector with the 1\/4 wave of wire that would be the stripped portion of coax and use a barrel connector (if necessary) to join the two.  <\/li>\n\n\n\n<li>Use ferrite beads and zip ties or tape for the choke placement.<\/li>\n<\/ul>\n\n\n\n<p>The 3 simple things make this antenna easier to build as you aren&#8217;t trying to strip 8&#8242; or more of outer insulation.  This might also lower the cost of the antenna as wire is cheaper than coax.  In the field one could change the radiating wire &amp; the position of the ferrite bead choke to change bands rather quickly.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>What is it: The basic premise of the antenna is strip the 1\/4 wave of shield off the coax, leave a 1\/4 wave of coax with shield, and choke before the before the physical feed point. This is resonant end-fed dipole, typically installed vertically. There are lots of plans for this on the internet, but [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"powered_cache_disable_cache":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-181","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/ka9kqh.net\/index.php?rest_route=\/wp\/v2\/posts\/181","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ka9kqh.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ka9kqh.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ka9kqh.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ka9kqh.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=181"}],"version-history":[{"count":3,"href":"https:\/\/ka9kqh.net\/index.php?rest_route=\/wp\/v2\/posts\/181\/revisions"}],"predecessor-version":[{"id":186,"href":"https:\/\/ka9kqh.net\/index.php?rest_route=\/wp\/v2\/posts\/181\/revisions\/186"}],"wp:attachment":[{"href":"https:\/\/ka9kqh.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=181"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ka9kqh.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=181"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ka9kqh.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=181"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}