{"id":5190,"date":"2015-06-09T09:09:00","date_gmt":"2015-06-08T23:09:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2015\/06\/09\/termination-insensitivity-only-three-tias-in-the-world\/"},"modified":"2025-07-21T18:29:47","modified_gmt":"2025-07-21T08:29:47","slug":"termination-insensitivity-only-three-tias-in-the-world","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2015\/06\/09\/termination-insensitivity-only-three-tias-in-the-world\/","title":{"rendered":"Termination Insensitivity &#8212; Only Three TIAs in the World?"},"content":{"rendered":"<div class=\"separator\" style=\"clear: both; text-align: center;\"> <a href=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2015\/06\/Pete2527sTIA.jpg\" imageanchor=\"1\" style=\"margin-left: 1em; margin-right: 1em;\"><img loading=\"lazy\" decoding=\"async\" border=\"0\" height=\"225\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2015\/06\/Pete2527sTIA.jpg\" width=\"400\" \/><\/a><\/div>\n<p> <strong>Termination Insensitivity. Is this like when your girlfriend dumps you and you just don&#8217;t care? <\/strong><br \/> <strong><\/strong><br \/> <strong>No. It&#8217;s more like this:<\/strong><br \/> <strong><\/strong><br \/> <a href=\"http:\/\/www.n6qw.com\/TIA.html\"><strong>http:\/\/www.n6qw.com\/TIA.html<\/strong><\/a><br \/> <strong><\/strong><br \/> <strong>Wes Hayward and Bob Kopski developed the <a href=\"http:\/\/w7zoi.net\/bidirectional_matched_amplifier.pdf\">Termination Insensitive Amplifier circuit<\/a> back in 2009. With a bidirectional rig it is important that the crystal filter face the same impedance in both directions. Simpler bidirectional amps are impedance &#8220;transparent&#8221; in that their input impedance depends on what is on the output (and vice versa). The circuit that Wes and Bob developed solved this problem: these amps always look like 50 ohms. That&#8217;s very useful. When I was building my earlier BITX rigs, Farhan suggested that I try the termination insensitive amp circuits. On my latest project I followed his suggestion. At the same time, Pete was building a new BITX, also using the TIA amps. <\/strong><br \/> <strong><\/strong><br \/> <strong>Pete wrote to Wes and Bob and asked if anyone had followed through on their 2009 article by building a rig using this circuit. Wes said that he was unaware of any TIA rigs. It turned out that Tom Hall up in New York City had built one (video below). So I guess Pete&#8217;s rig is TIA 2 and mine is TIA 3! (But I was thinking, because of Pete&#8217;s Italian ancestry, shouldn&#8217;t we call his rig a Zia?)<\/strong><br \/> <strong>Please let us know if you know of any other TIAS (or ZIAS!) out there. <\/strong><br \/> <strong><\/strong><br \/> <strong>Here is Tom Hall&#8217;s very FB TIA: <\/strong><\/p>\n<p> <iframe loading=\"lazy\" allowfullscreen=\"\" frameborder=\"0\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/V_uBqbEV0-w?rel=0\" width=\"420\"><\/iframe> <\/p>\n<p> Our book: &#8220;SolderSmoke &#8212; Global Adventures in Wireless Electronics&#8221; <a href=\"http:\/\/soldersmoke.com\/book.htm\">http:\/\/soldersmoke.com\/book.htm<\/a> Our coffee mugs, T-Shirts, bumper stickers: <a href=\"http:\/\/www.cafepress.com\/SolderSmoke\">http:\/\/www.cafepress.com\/SolderSmoke<\/a> Our Book Store: <a href=\"http:\/\/astore.amazon.com\/contracross-20\">http:\/\/astore.amazon.com\/contracross-20<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Termination Insensitivity. Is this like when your girlfriend dumps you and you just don&#8217;t care? No. It&#8217;s more like this: http:\/\/www.n6qw.com\/TIA.html Wes Hayward and Bob Kopski developed the Termination Insensitive Amplifier circuit back in 2009. With a bidirectional rig it is important that the crystal filter face the same impedance in both directions. Simpler bidirectional &hellip; <a href=\"https:\/\/www.homebrewradio.us\/blog\/2015\/06\/09\/termination-insensitivity-only-three-tias-in-the-world\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Termination Insensitivity &#8212; Only Three TIAs in the World?&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":5191,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[193,28,66,60,251],"tags":[],"class_list":["post-5190","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bitx-digi-tia","category-bitx20","category-farhan","category-hayward-wes","category-new-york-city"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5190","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\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=5190"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5190\/revisions"}],"predecessor-version":[{"id":5192,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5190\/revisions\/5192"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/5191"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=5190"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=5190"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=5190"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}