{"id":179,"date":"2018-10-16T22:15:08","date_gmt":"2018-10-16T11:15:08","guid":{"rendered":"http:\/\/www.vk1zdj.net\/?p=179"},"modified":"2022-12-19T14:55:32","modified_gmt":"2022-12-19T03:55:32","slug":"a-slightly-toasted-icom-ah4-antenna-tuner","status":"publish","type":"post","link":"http:\/\/www.vk1zdj.net\/?p=179","title":{"rendered":"A Slightly Toasted Icom AH4 Antenna Tuner"},"content":{"rendered":"<p>I purchased a slightly toasted AH4 tuner, which had clearly been overloaded during the tune cycle.<\/p>\n<p>The power attenuator had been thoroughly cooked.<\/p>\n<p>I spent a couple of afternoons removing the burnt area of the PCB using a high speed rotary tool.\u00a0 then I re built the missing PCB using fiberglass matting and epoxy resin.\u00a0 Finally I made new PCB traces from copper foil to allow new attenuation resistors to be added.<\/p>\n<p><a href=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151554.jpg\"><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-172\" src=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151554-300x169.jpg\" alt=\"\" width=\"300\" height=\"169\" srcset=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151554-300x169.jpg 300w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151554-768x432.jpg 768w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151554-1024x576.jpg 1024w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151554-80x45.jpg 80w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>Sadly there was nothing to see on the top side of the board &#8211; Just a big black charred mess. This is the back of the board that gives a clue.<\/p>\n<p><a href=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_142230.jpg\"><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-177\" src=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_142230-300x169.jpg\" alt=\"\" width=\"300\" height=\"169\" srcset=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_142230-300x169.jpg 300w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_142230-768x432.jpg 768w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_142230-1024x576.jpg 1024w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_142230-80x45.jpg 80w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>This is the board after the charred area was removed, resin applied and new tracks cut out.<\/p>\n<p><a href=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151601.jpg\"><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-173\" src=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_151601-300x169.jpg\" alt=\"\" width=\"300\" height=\"169\" \/><\/a><\/p>\n<p>This is the repair after adding new components.<\/p>\n<p><a href=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_134356.jpg\"><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-medium wp-image-175\" src=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_134356-300x169.jpg\" alt=\"\" width=\"300\" height=\"169\" srcset=\"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_134356-300x169.jpg 300w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_134356-768x432.jpg 768w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_134356-1024x576.jpg 1024w, http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_134356-80x45.jpg 80w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>And finally &#8211; A reference photo that shows what it should have looked like before it was cooked.<\/p>\n<p>After the repair, I followed the alignment instructions in the service manual.\u00a0 It works like a charm.\u00a0 Another piece of gear saved from the scrapheap.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I purchased a slightly toasted AH4 tuner, which had clearly been overloaded during the tune cycle. The power attenuator had been thoroughly cooked. I spent a couple of afternoons removing the burnt area of the PCB using a&#8230; <\/p>\n","protected":false},"author":1,"featured_media":171,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false},"categories":[6],"tags":[],"jetpack_featured_media_url":"http:\/\/www.vk1zdj.net\/wp-content\/uploads\/2019\/08\/20161111_150341.jpg","_links":{"self":[{"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/posts\/179"}],"collection":[{"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=179"}],"version-history":[{"count":4,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/posts\/179\/revisions"}],"predecessor-version":[{"id":622,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/posts\/179\/revisions\/622"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=\/wp\/v2\/media\/171"}],"wp:attachment":[{"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=179"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=179"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.vk1zdj.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=179"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}