{"id":6504,"date":"2026-02-24T17:53:36","date_gmt":"2026-02-24T22:53:36","guid":{"rendered":"https:\/\/www.summet.com\/blog\/?p=6504"},"modified":"2026-02-24T17:58:23","modified_gmt":"2026-02-24T22:58:23","slug":"installing-a-narrow-cw-filter-into-an-icom-ic-725-ham-transceiver","status":"publish","type":"post","link":"https:\/\/www.summet.com\/blog\/2026\/02\/24\/installing-a-narrow-cw-filter-into-an-icom-ic-725-ham-transceiver\/","title":{"rendered":"Installing a Narrow CW filter into an iCom  IC-725 HAM Transceiver"},"content":{"rendered":"<p><iframe loading=\"lazy\" title=\"YouTube video player\" src=\"https:\/\/www.youtube-nocookie.com\/embed\/2xFMR_f_U1M?si=JAH99P10o2OgEyBE\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><br \/>\nThe iCom IC-725 Transceiver receives CW (Morse Code) natively, but you can install an optional &#8220;narrow&#8221; CW filter that gives you greater sensitivity \/ out of band rejection.<\/p>\n<p><a href=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/optional-narrow-filters.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-6508\" src=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/optional-narrow-filters.png\" alt=\"\" width=\"547\" height=\"595\" srcset=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/optional-narrow-filters.png 547w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/optional-narrow-filters-276x300.png 276w\" sizes=\"auto, (max-width: 547px) 100vw, 547px\" \/><\/a><\/p>\n<p>The FL-100 (500Hz notch) or FL-101 (250 Hz notch) are suggested in the IC-725 manual. I instead installed a FL-232 (350Hz) filter which is designed for later ICOM radios, but has the same form factor, and is designed for the same 9.01 Mhz IF that the IC-725 uses. This is a &#8220;happy medium&#8221; between the 500 and 250 sizes (Plus, I found a FL-232 for sale at $87 shipped, while most of the FL-100 and FL-101&#8217;s I&#8217;ve seen for sale are $120-150 shipped from Japan.)<\/p>\n<p><!--more--><\/p>\n<p><a href=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-large wp-image-6505\" src=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual-1024x576.png\" alt=\"\" width=\"584\" height=\"329\" srcset=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual-1024x576.png 1024w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual-300x169.png 300w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual-768x432.png 768w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual-1536x864.png 1536w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual-500x281.png 500w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/02\/filter-install-manual.png 1544w\" sizes=\"auto, (max-width: 584px) 100vw, 584px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>Installation requires you to open the bottom cover of the radio, but is not otherwise difficult, as the circuit board has sockets underneath, making it a simple &#8220;plug in&#8221; install. I was lucky enough that the used FL-232 filter I purchased came with the thin clear rubber &#8220;anti-vibration&#8221; pad, which prevents from inadvertent short circuits and makes it less likely to detach.\u00a0 The location is clearly labeled &#8220;CW Filter&#8221; and a white rectangle, directly in front of the (pre-installed) SSB filter. You can install the filter in either orientation, but I did it with the iCom sticker facing the same way as the one on the SSB filter.\u00a0 Watch the end of the video above to hear the difference in discrimination between the &#8220;normal&#8221; CW setting and the &#8220;Narrow&#8221; CW setting after the filter is installed. [Before the filter is installed, if you select CW-N mode, the radio goes silent, as it can&#8217;t pass any signal through the non-existant filer.]<\/p>\n<p><a href=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/01\/CW-filter-closeup.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-6452\" src=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/01\/CW-filter-closeup.png\" alt=\"\" width=\"747\" height=\"588\" srcset=\"https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/01\/CW-filter-closeup.png 747w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/01\/CW-filter-closeup-300x236.png 300w, https:\/\/www.summet.com\/blog\/wp-content\/uploads\/2026\/01\/CW-filter-closeup-381x300.png 381w\" sizes=\"auto, (max-width: 747px) 100vw, 747px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The iCom IC-725 Transceiver receives CW (Morse Code) natively, but you can install an optional &#8220;narrow&#8221; CW filter that gives you greater sensitivity \/ out of band rejection. The FL-100 (500Hz notch) or FL-101 (250 Hz notch) are suggested in &hellip; <a href=\"https:\/\/www.summet.com\/blog\/2026\/02\/24\/installing-a-narrow-cw-filter-into-an-icom-ic-725-ham-transceiver\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[162,163],"class_list":["post-6504","post","type-post","status-publish","format-standard","hentry","category-projects","tag-ham","tag-ic-725"],"_links":{"self":[{"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/posts\/6504","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/comments?post=6504"}],"version-history":[{"count":3,"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/posts\/6504\/revisions"}],"predecessor-version":[{"id":6509,"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/posts\/6504\/revisions\/6509"}],"wp:attachment":[{"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/media?parent=6504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/categories?post=6504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.summet.com\/blog\/wp-json\/wp\/v2\/tags?post=6504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}