{"id":62,"date":"2015-02-03T20:15:34","date_gmt":"2015-02-03T19:15:34","guid":{"rendered":"https:\/\/pa3csg.nl\/?page_id=62"},"modified":"2016-06-06T10:56:04","modified_gmt":"2016-06-06T08:56:04","slug":"70-mhz-bandpass-filter","status":"publish","type":"page","link":"https:\/\/pa3csg.nl\/?page_id=62","title":{"rendered":"70 MHz bandpass filter"},"content":{"rendered":"<h1>70 MHz bandpass filter<\/h1>\n<p>When working on the 144 MHz bandpass filters, these were tunable over such a wide range that 70 MHz was almost in reach. Changing the\u00a0 3pF capacitor for a 22 pF version did the job. The tuning was not optimum, it would have been better to use 10 pF caps and maybe a 6.5 turn inductor. Anyway with the 6 turn inductor it was a nice filter.<\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-inside.jpg\" data-rel=\"lightbox-image-0\" data-rl_title=\"\" data-rl_caption=\"\"><img loading=\"lazy\" class=\"alignnone size-full wp-image-499\" title=\"\" src=\"https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-inside.jpg\" width=\"500\" height=\"505\" srcset=\"https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-inside.jpg 500w, https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-inside-297x300.jpg 297w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>The plot for this filter. Vertical is 10dB per division, horizontal each division is 4 MHz.<\/p>\n<p style=\"text-align: center;\">\n<p style=\"text-align: center;\"><a href=\"https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-plot.jpg\" data-rel=\"lightbox-image-1\" data-rl_title=\"\" data-rl_caption=\"\"><img loading=\"lazy\" class=\"alignnone size-full wp-image-500\" title=\"\" src=\"https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-plot.jpg\" width=\"500\" height=\"453\" srcset=\"https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-plot.jpg 500w, https:\/\/pa3csg.nl\/wp-content\/uploads\/2016\/06\/4m-helical-bp-plot-300x272.jpg 300w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<p>In this configuration 50 MHz could not be tuned.<\/p>\n<p>If you want to see the original article click <a href=\"https:\/\/pa3csg.nl\/?page_id=61\" target=\"_self\">HERE<\/a><\/p>\n<p>Click <a href=\"https:\/\/pa3csg.nl\/?page_id=63\" target=\"_self\">HERE<\/a> for a 50 MHz version.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<div class=\"mh-excerpt\"><p>70 MHz bandpass filter When working on the 144 MHz bandpass filters, these were tunable over such a wide range that 70 MHz was almost <a class=\"mh-excerpt-more\" href=\"https:\/\/pa3csg.nl\/?page_id=62\" title=\"70 MHz bandpass filter\">[&#8230;]<\/a><\/p>\n<\/div>","protected":false},"author":1,"featured_media":500,"parent":0,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"categories":[38,16],"tags":[],"_links":{"self":[{"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/pages\/62"}],"collection":[{"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=62"}],"version-history":[{"count":5,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/pages\/62\/revisions"}],"predecessor-version":[{"id":502,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/pages\/62\/revisions\/502"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=\/wp\/v2\/media\/500"}],"wp:attachment":[{"href":"https:\/\/pa3csg.nl\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=62"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=62"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pa3csg.nl\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=62"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}