{"id":1662,"date":"2011-10-18T09:21:00","date_gmt":"2011-10-17T22:21:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2011\/10\/18\/my-jbot-5-watt-linear-farhans-design\/"},"modified":"2025-07-21T11:55:42","modified_gmt":"2025-07-21T01:55:42","slug":"my-jbot-5-watt-linear-farhans-design","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2011\/10\/18\/my-jbot-5-watt-linear-farhans-design\/","title":{"rendered":"My JBOT 5 Watt Linear (Farhan&#8217;s Design)"},"content":{"rendered":"<p><a onblur=\"try {parent.deselectBloggerImageGracefully();} catch(e) {}\" href=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2011\/10\/JBOTCLOSE.jpg\"><img decoding=\"async\" style=\"display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 299px;\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2011\/10\/JBOTCLOSE.jpg\" alt=\"\" id=\"BLOGGER_PHOTO_ID_5664761442411135314\" border=\"0\" \/><\/a><span style=\"font-size:130%;\"><span style=\"font-weight: bold;\">There it is &#8212; my version of <a href=\"http:\/\/www.phonestack.com\/farhan\/jbot.html\">Farhan&#8217;s JBOT 5 watt linear amplifier<\/a>. JBOT stands for &#8220;Just a Bunch of Transistors.&#8221; But I think Farhan is being modest. I really like the design, especially the effort to make this something that hams around the world can reproduce from readily available parts. For example, Farhan&#8217;s original version used TV balun cores for the transformers. I didn&#8217;t have any of those around, but I found three &#8220;mystery spec&#8221; binocular cores in my junk box. They seem to be working just fine. (I tested them a bit: Farhan had written that FT 37-43 cores would work. T1 has seven turns trifilar. Seven turns on my mystery cores yielded 13uH. On an FT 37-43 core 7 turns yields around 20 uH. Close enough &#8212; these are, after all, broadband transformers.)<\/span><\/p>\n<p><span style=\"font-weight: bold;\">Note how closely my build follows Farhan&#8217;s schematic (which you can see in the background). When building this circuit, I just kept Farhan&#8217;s web page on my computer screen, and scrolled up and down from his schematic to the photo of his version.<\/span><\/p>\n<p><span style=\"font-weight: bold;\">This is the first linear amplifier that worked the first time I powered it up. It didn&#8217;t release any smoke, or leave transistor burn tattoos on fingers, or try to be a 14MHz oscillator.<\/span><\/p>\n<p><span style=\"font-weight: bold;\">This version is going into <a href=\"http:\/\/www.gadgeteer.us\/17METER.HTM\">my Azores-built 17 meter DSB transceiver<\/a>. See how nice it fits:<\/span><\/span><br \/><a href=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2011\/10\/JBOTinDSBRIG.jpg\"><img decoding=\"async\" style=\"display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 299px;\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2011\/10\/JBOTinDSBRIG.jpg\" alt=\"\" id=\"BLOGGER_PHOTO_ID_5664764531633118242\" border=\"0\" \/><\/a>Our book: &#8220;SolderSmoke &#8212; Global Adventures in Wireless Electronics&#8221;<a href=\"http:\/\/soldersmoke.com\/book.htm\">http:\/\/soldersmoke.com\/book.htm<\/a>Our coffee mugs, T-Shirts, bumper stickers: <a href=\"http:\/\/www.cafepress.com\/SolderSmoke\">http:\/\/www.cafepress.com\/SolderSmoke<\/a>Our Book Store: <a href=\"http:\/\/astore.amazon.com\/contracross-20\">http:\/\/astore.amazon.com\/contracross-20<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>There it is &#8212; my version of Farhan&#8217;s JBOT 5 watt linear amplifier. JBOT stands for &#8220;Just a Bunch of Transistors.&#8221; But I think Farhan is being modest. I really like the design, especially the effort to make this something that hams around the world can reproduce from readily available parts. For example, Farhan&#8217;s original &hellip; <a href=\"https:\/\/www.homebrewradio.us\/blog\/2011\/10\/18\/my-jbot-5-watt-linear-farhans-design\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;My JBOT 5 Watt Linear (Farhan&#8217;s Design)&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":1663,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[84,164,33,66,68,235],"tags":[],"class_list":["post-1662","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-amplifier-theory","category-azores","category-dsb","category-farhan","category-india","category-jbot"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/1662","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=1662"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/1662\/revisions"}],"predecessor-version":[{"id":1665,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/1662\/revisions\/1665"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/1663"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=1662"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=1662"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=1662"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}