{"id":413,"date":"2026-10-15T18:06:34","date_gmt":"2026-10-16T00:06:34","guid":{"rendered":"http:\/\/aa6kj.hopto.org\/wp\/?p=413"},"modified":"2026-10-15T18:11:44","modified_gmt":"2026-10-16T00:11:44","slug":"controlling-kd9sv-160-m-preamp-with-computer","status":"publish","type":"post","link":"http:\/\/aa6kj.hopto.org\/wp\/?p=413","title":{"rendered":"Controlling KD9SV 160 m preamp with computer"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">I have KD9SV 160 m preamp that I would like to use on 160 m only and have it turned off for all other bands. This unit does not have any computer control &#8211; just the old style rocker switch to turn it on\/off. So, I decided to keep this manual switch in the on position all them time and install USB relay to control the 12 V power to the unit. This cheap USB relay switch seems to work well (model DSD TECH SH-UR01A):<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"425\" height=\"425\" src=\"http:\/\/aa6kj.hopto.org\/wp\/wp-content\/uploads\/2026\/10\/image.png\" alt=\"\" class=\"wp-image-414\" style=\"width:193px;height:auto\" srcset=\"http:\/\/aa6kj.hopto.org\/wp\/wp-content\/uploads\/2026\/10\/image.png 425w, http:\/\/aa6kj.hopto.org\/wp\/wp-content\/uploads\/2026\/10\/image-300x300.png 300w, http:\/\/aa6kj.hopto.org\/wp\/wp-content\/uploads\/2026\/10\/image-150x150.png 150w, http:\/\/aa6kj.hopto.org\/wp\/wp-content\/uploads\/2026\/10\/image-200x200.png 200w\" sizes=\"auto, (max-width: 425px) 100vw, 425px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">It sells for $15 on Amazon. It appears as a RS-232 device on the computer (Linux system in my case), which requires baud rate of 9600, 8 data bits and no parity. To turn the relay on, use:<\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\">AT+CH1=1<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">and to turn it off use:<\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\">AT+CH1=0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Note that newline or carriage return should not be sent. I use this in my antenna control program (ant.c) where I now have a button to toggle the preamp state.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I have KD9SV 160 m preamp that I would like to use on 160 m only and have it turned off for all other bands. This unit does not have any computer control &#8211; just the old style rocker switch to turn it on\/off. So, I decided to keep this manual switch in the on [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-413","post","type-post","status-publish","format-standard","hentry","category-ham_radio"],"_links":{"self":[{"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/413","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=413"}],"version-history":[{"count":4,"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/413\/revisions"}],"predecessor-version":[{"id":419,"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/413\/revisions\/419"}],"wp:attachment":[{"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=413"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=413"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/aa6kj.hopto.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=413"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}