{"id":16508,"date":"2026-02-11T12:38:15","date_gmt":"2026-02-11T07:08:15","guid":{"rendered":"https:\/\/johnsonfrancis.org\/techworld\/?p=16508"},"modified":"2026-02-11T19:17:01","modified_gmt":"2026-02-11T13:47:01","slug":"digital-temperature-controller-thermostat-w1209-for-evq-linear","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/techworld\/digital-temperature-controller-thermostat-w1209-for-evq-linear\/","title":{"rendered":"Digital temperature controller thermostat (W1209) for EVQ linear!"},"content":{"rendered":"<iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/l92SA-gR5Dw?si=s9lNoVLRtObmrCxe\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n\n<p class=\"wp-block-paragraph\">Yesterday I had posted about plans to implement thermal protection for my homebrew HF linear amplifier of VU2EVQ design. Had ordered a <a href=\"https:\/\/amzn.to\/46vGAuU\" type=\"link\" id=\"https:\/\/amzn.to\/46vGAuU\">digital temperature controller thermostat from Amazon<\/a> yesterday evening. Surprisingly, it arrived today morning. May be it is being stocked somewhere near! It has a NTC (10K 0.5%) Waterproof sensor. That should be a Negative Temperature Coefficient Thermistor. Control range is mentioned as 50 ~ 110, with control accuracy: 0.1. The device weighs only 80 grams. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">We have to press the SET key to enter the setup. When the display flashes, press &#8220;+&#8221; &#8220;-&#8221; to change temperature settings. Then a long press of SET or leave 10 seconds without button operation, and the controller automatically confirms completion. The digital sensor displays 888 when it is open, HHH for the excess of the maximum temperature of the measuring range, LLL of the measuring range of the lowest temperature. In both situations the thermostat will force off the relay. These details are from the supplier. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">There is another page here which gives more detailed information: <a href=\"https:\/\/support.envistiamall.com\/kb\/w1209-12v-50-to-110c-digital-thermostat-temperature-controller-module-installation-and-operating-instructions\/\" type=\"link\" id=\"https:\/\/support.envistiamall.com\/kb\/w1209-12v-50-to-110c-digital-thermostat-temperature-controller-module-installation-and-operating-instructions\/\">W1209 12V -50\u00b0 to 110\u00b0C Digital Thermostat Temperature Controller Module Installation and Operating Instructions<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Please note that the Amazon link is an affiliate link and Amazon will pay me a tiny amount if you buy using that link, at no extra cost to the buyer.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Yesterday I had posted about plans to implement thermal protection for my homebrew HF linear amplifier of VU2EVQ design. Had ordered a digital temperature controller thermostat from Amazon yesterday evening. Surprisingly, it arrived today morning. May be it is being stocked somewhere near! It has a NTC (10K 0.5%) Waterproof sensor. That should be a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":16512,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-16508","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-amateur-radio-ham-radio"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Digital temperature controller thermostat (W1209) for EVQ linear! - Johnson&#039;s Techworld<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/johnsonfrancis.org\/techworld\/digital-temperature-controller-thermostat-w1209-for-evq-linear\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Digital temperature controller thermostat (W1209) for EVQ linear! - Johnson&#039;s Techworld\" \/>\n<meta property=\"og:description\" content=\"Yesterday I had posted about plans to implement thermal protection for my homebrew HF linear amplifier of VU2EVQ design. Had ordered a digital temperature controller thermostat from Amazon yesterday evening. Surprisingly, it arrived today morning. May be it is being stocked somewhere near! It has a NTC (10K 0.5%) Waterproof sensor. That should be a [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/johnsonfrancis.org\/techworld\/digital-temperature-controller-thermostat-w1209-for-evq-linear\/\" \/>\n<meta property=\"og:site_name\" content=\"Johnson&#039;s Techworld\" \/>\n<meta property=\"article:published_time\" content=\"2026-02-11T07:08:15+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-02-11T13:47:01+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/johnsonfrancis.org\/techworld\/wp-content\/uploads\/2026\/02\/Digital-temperature-controller-thermostat.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1209\" \/>\n\t<meta property=\"og:image:height\" content=\"675\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Johnson Francis\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Johnson Francis\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/digital-temperature-controller-thermostat-w1209-for-evq-linear\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/digital-temperature-controller-thermostat-w1209-for-evq-linear\\\/\"},\"author\":{\"name\":\"Johnson Francis\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/#\\\/schema\\\/person\\\/6201c843e80ccd3578e6196b1d007027\"},\"headline\":\"Digital temperature controller thermostat (W1209) for EVQ linear!\",\"datePublished\":\"2026-02-11T07:08:15+00:00\",\"dateModified\":\"2026-02-11T13:47:01+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/digital-temperature-controller-thermostat-w1209-for-evq-linear\\\/\"},\"wordCount\":219,\"publisher\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/#\\\/schema\\\/person\\\/6201c843e80ccd3578e6196b1d007027\"},\"image\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/digital-temperature-controller-thermostat-w1209-for-evq-linear\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/wp-content\\\/uploads\\\/2026\\\/02\\\/Digital-temperature-controller-thermostat.jpg\",\"articleSection\":[\"Amateur Radio (Ham Radio)\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/digital-temperature-controller-thermostat-w1209-for-evq-linear\\\/\",\"url\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/digital-temperature-controller-thermostat-w1209-for-evq-linear\\\/\",\"name\":\"Digital temperature controller thermostat (W1209) for EVQ linear! 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