{"id":7387,"date":"2026-10-08T17:08:08","date_gmt":"2026-10-08T21:08:08","guid":{"rendered":"https:\/\/stonemountainhamfest.com\/?page_id=7387"},"modified":"2026-10-11T17:33:56","modified_gmt":"2026-10-11T21:33:56","slug":"end-fed-random-wire-qrp-antenna","status":"publish","type":"page","link":"https:\/\/stonemountainhamfest.com\/index.php\/end-fed-random-wire-qrp-antenna\/","title":{"rendered":"End Fed Random Wire <br>( QRP Antenna )"},"content":{"rendered":"<body><p><\/p><strong><span style=\"color: #0000ff;\">Presenter:<\/span>\u00a0 <\/strong>Steve Hudson, <a href=\"https:\/\/www.qrz.com\/db\/AA4BW\" target=\"_blank\" rel=\"noopener\">AA4BW<\/a>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\"><strong>FRIDAY AFTERNOON BUILDING SESSION<\/strong><\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\"><strong>Friday afternoon, 3-5 p.m.<\/strong><\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\"><strong>Build A Self-Contained End Fed Random Wire Antenna (QRP Version, up to 10W CW \/ 20W PEP SSB)<\/strong><\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\"><strong>Cost of kit\/instructions: $40<\/strong><\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">\u00a0<\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">Hams who enjoy POTA, SOTA and other portable operation have discovered that the End Fed Random Wire antenna is an effective option when operating in the field \u2014 and on Friday afternoon participants in this Building Session will construct a complete 40-10 meter \u201cEFRW\u201d system of their own!<\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">\u00a0<\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">End Fed Random Wires are really not random at all but are actually cut to carefully chosen lengths that are NOT resonant on any band of interest.\u00a0 Typically, their feed impedance is several hundred ohms.\u00a0 EFRW designs such as this one usually assume a 450 ohm feed impedance for design purposes and use a 9:1 impedance transformer to step that impedance to something between, say, 25 ohms and 100 ohms.\u00a0 Feed impedances in that range are easy for almost any antenna tuner to handle, and the result is an extremely frequency-agile multi-band antenna.<\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">\u00a0<\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">Please note that you will need to use a tuner with this antenna, but virtually every built-in tuner or outboard tuner will handle that matching task easily.<\/div>\n<div>\u00a0<\/div>\n<div><img data-recalc-dims=\"1\" decoding=\"async\" class=\"aligncenter size-large wp-image-7400\" src=\"https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP.jpeg?resize=474%2C356&#038;ssl=1\" alt=\"\" width=\"474\" height=\"356\" loading=\"lazy\" srcset=\"https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?resize=1024%2C768&amp;ssl=1 1024w, https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?resize=300%2C225&amp;ssl=1 300w, https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?resize=768%2C576&amp;ssl=1 768w, https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?resize=1536%2C1152&amp;ssl=1 1536w, https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?resize=2048%2C1536&amp;ssl=1 2048w, https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?w=948&amp;ssl=1 948w, https:\/\/i0.wp.com\/stonemountainhamfest.com\/wp-content\/uploads\/2026\/10\/OCF_20w-QRP-scaled.jpeg?w=1422&amp;ssl=1 1422w\" sizes=\"auto, (max-width: 474px) 100vw, 474px\" \/><\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">\u00a0<\/div>\n<div class=\"yiv1927409772ydp42b46573yiv5166856370default-style\">This unique project is a self-contained and easily portable system built around (and IN!) a handheld antenna winder!\u00a0 Built using an FT82-43 core, the matching system is conservatively rated for 10 watts CW or 20 watts PEP SSB.\u00a0 Of course, you\u2019ll need to derate it if using digital modes.<\/div>\n<div class=\"yiv1927409772default-style yiv1927409772ydp42b46573yiv5166856370default-style\">\u00a0<\/div>\n<div class=\"yiv1927409772default-style yiv1927409772ydp42b46573yiv5166856370default-style\">The unit you\u2019ll build features a BNC connector for connecting to your radio, plus a captive-wingnut connection post for attaching the antenna wire.\u00a0 In the interest of simplicity in the field and ease of construction, the counterpoise connection on this antenna system is made via a crocodile clip.<\/div>\n<div class=\"yiv1927409772default-style yiv1927409772ydp42b46573yiv5166856370default-style\">\u00a0<\/div>\n<div class=\"yiv1927409772default-style yiv1927409772ydp42b46573yiv5166856370default-style\">The kit includes all parts and hardware needed to build the matching unit and winder system, plus the antenna wire (about 29 ft in this case) and counterpoise wire (about 17 ft).\u00a0 Also included are detailed and fully illustrated instructions.<\/div>\n<div>\u00a0<\/div>\n<div><span style=\"color: #0000ff;\"><strong>Sign-Up Here:<\/strong>\u00a0<\/span> <a href=\"https:\/\/forms.gle\/1SRQVirpY46gBfFA6\" target=\"_blank\" rel=\"noopener\">On This Google Form<\/a><\/div>\n<div>\n<div>\n<div>Note:\u00a0 Each Antenna Project has its own sign-up page.\u00a0 We have set a limit of 12 for each antenna build but are allowing 16 to sign up just in case of no-shows.<\/div>\n<\/div>\n<div>\u00a0<\/div>\n<div><span style=\"color: #0000ff;\"><strong>Return to: <\/strong><\/span><a href=\"https:\/\/stonemountainhamfest.com\/index.php\/antenna-building-days-at-the-hamfest\/\">The Antenna Build Project Page<\/a><\/div>\n<\/div>\n<div>\n<hr>\n<\/div>\n<p>\u00a0<\/p>\n<\/body>","protected":false},"excerpt":{"rendered":"<p>Presenter:\u00a0 Steve Hudson, AA4BW FRIDAY AFTERNOON BUILDING SESSION Friday afternoon, 3-5 p.m. Build A Self-Contained End Fed Random Wire Antenna (QRP Version, up to 10W CW \/ 20W PEP SSB) Cost of kit\/instructions: $40 \u00a0 Hams who enjoy POTA, SOTA and other portable operation have discovered that the End Fed Random Wire antenna is an &hellip; <a href=\"https:\/\/stonemountainhamfest.com\/index.php\/end-fed-random-wire-qrp-antenna\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">End Fed Random Wire <br \/>( QRP Antenna )<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":10,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"ngg_post_thumbnail":0,"footnotes":""},"class_list":["post-7387","page","type-page","status-publish","hentry"],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/pages\/7387","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/users\/10"}],"replies":[{"embeddable":true,"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/comments?post=7387"}],"version-history":[{"count":5,"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/pages\/7387\/revisions"}],"predecessor-version":[{"id":7434,"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/pages\/7387\/revisions\/7434"}],"wp:attachment":[{"href":"https:\/\/stonemountainhamfest.com\/index.php\/wp-json\/wp\/v2\/media?parent=7387"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}