{"id":210,"date":"2024-03-06T12:46:00","date_gmt":"2024-03-06T01:46:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2024\/03\/06\/n6asd-builds-a-zinc-oxide-negative-resistance-transmitter-and-a-spark-coherer-rig\/"},"modified":"2025-07-22T18:01:42","modified_gmt":"2025-07-22T08:01:42","slug":"n6asd-builds-a-zinc-oxide-negative-resistance-transmitter-and-a-spark-coherer-rig","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2024\/03\/06\/n6asd-builds-a-zinc-oxide-negative-resistance-transmitter-and-a-spark-coherer-rig\/","title":{"rendered":"N6ASD Builds a Zinc-Oxide Negative Resistance Transmitter (and a Spark\/Coherer rig)"},"content":{"rendered":"<p><iframe loading=\"lazy\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen=\"\" frameborder=\"0\" height=\"247\" src=\"https:\/\/www.youtube.com\/embed\/LfUABN_HGwU?si=xXO-3RA-roZ_KQ9l?rel=0\" title=\"YouTube video player\" width=\"440\"><\/iframe><\/p>\n<div><\/div>\n<div><span style=\"font-size: medium;\"><b>I saw this video and post on Hackaday this morning:<\/b><\/span><\/div>\n<div><span style=\"font-size: medium;\"><b><br \/><\/b><\/span><\/div>\n<div><a href=\"https:\/\/hackaday.com\/2024\/03\/05\/making-a-crystodyne-radio-with-zinc-oxide-and-cats-whiskers\/\"><span style=\"font-size: medium;\"><b>https:\/\/hackaday.com\/2024\/03\/05\/making-a-crystodyne-radio-with-zinc-oxide-and-cats-whiskers\/<\/b><\/span><\/a><\/div>\n<div><span style=\"font-size: medium;\"><b><br \/><\/b><\/span><\/div>\n<div><span style=\"font-size: medium;\"><b>I got the fellow&#8217;s callsign from his Morse CQ. <\/b><\/span><\/div>\n<div><span style=\"font-size: medium;\"><b>It is N6ASD in San Francisco. <\/b><\/span><\/div>\n<div><span style=\"font-size: medium;\"><b><br \/><\/b><\/span><\/div>\n<div><span style=\"font-size: medium;\"><b>Check this out from his QRZ page:<a href=\"https:\/\/www.qrz.com\/db\/N6ASD\"> https:\/\/www.qrz.com\/db\/N6ASD<\/a><\/b><\/span><\/div>\n<div><\/div>\n<div>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">My journey into the world of amateur radio began in a very primitive way. My first &#8220;rig&#8221; comprised of a spark-gap transmitter and a coherer based receiver. A coherer is a primitive radio signal detector that consists of iron filings placed between two electrodes. It was popular in the early days of wireless telegraphy.<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">Spark transmitter (using a car&#8217;s ignition coil to generate high-voltage sparks):<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\"><input alt=\"Spark transmitter\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2024\/03\/spark_transmitter.png\" style=\"height: 225px; width: 400px;\" type=\"image\" \/><\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">Coherer based receiver (using a doorbell for the &#8220;decoherer&#8221; mechanism):<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\"><input alt=\"Coherer receiver\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2024\/03\/coherer_receiver.jpg\" style=\"height: 267px; width: 400px;\" type=\"image\" \/><\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">When I keyed the transmitter, a high voltage arc would appear at the spark-gap and this produced (noisy) radio waves. The signal would be received by the iron-filings coherer on the other side of the room. A coherer is (usually) a one-shot receiver. You have to physically hit it to shake the filings and bring the detector back to its original state. That&#8217;s what the doorbell hammer did. It would hit the coherer every time it received a signal. It amazed me to no end. A spark created in one room of my house could make the hammer move in another room. Magic!<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">Soon after this project, I started experimenting with *slightly more refined* crystal detectors and crystal radio circuits. As most of you would know, these amazing radios don&#8217;t require any batteries and work by harnessing energy from radio waves. I guess these simple experiments instilled a sense of awe and wonder regarding electromagnetic waves, and eventually, this brought me into the world of amateur radio in 2015.<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">My main HF rig is an old ICOM IC-735. The only modification on this is radio is that it uses LED backlights (instead of bulbs):<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\"><img decoding=\"async\" alt=\"Icom IC 735\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2024\/03\/icom_735.jpg\" style=\"height: 282px; width: 500px;\" \/><\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\"><img decoding=\"async\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2024\/03\/shack_png.jpg\" style=\"height: 282px; width: 500px;\" \/><\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">With space at a premium in San Francisco, the antenna that I have settled for is an inverted vee installed in my backyard (and it just barely fits). I made the mast by lashing together wooden planks. For this city dweller, it works FB:<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\"><img decoding=\"async\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2024\/03\/ant1.png\" style=\"height: 711px; width: 400px;\" \/><\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">I have recently gotten into CW, and it has definitely become my mode of choice.<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">I&#8217;m a self-taught electronics enthusiast and I love homebrewing radio circuits. I&#8217;ll be sharing more info about them soon.<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">Thanks for checking out my page. I hope to meet you on the air!<\/p>\n<p style=\"background-color: white; font-family: \"Lucida Grande\", \"Lucida Sans\", Arial, sans-serif; font-size: 17.6px;\">73,<br \/>N6ASD<\/p>\n<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>I saw this video and post on Hackaday this morning: https:\/\/hackaday.com\/2024\/03\/05\/making-a-crystodyne-radio-with-zinc-oxide-and-cats-whiskers\/ I got the fellow&#8217;s callsign from his Morse CQ. It is N6ASD in San Francisco. Check this out from his QRZ page: https:\/\/www.qrz.com\/db\/N6ASD My journey into the world of amateur radio began in a very primitive way. My first &#8220;rig&#8221; comprised of a spark-gap &hellip; <a href=\"https:\/\/www.homebrewradio.us\/blog\/2024\/03\/06\/n6asd-builds-a-zinc-oxide-negative-resistance-transmitter-and-a-spark-coherer-rig\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;N6ASD Builds a Zinc-Oxide Negative Resistance Transmitter (and a Spark\/Coherer rig)&#8221;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":211,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[108,31],"tags":[],"class_list":["post-210","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-crystal-radio","category-radio-history"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/210","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\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=210"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/210\/revisions"}],"predecessor-version":[{"id":216,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/210\/revisions\/216"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/211"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=210"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=210"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}