{"id":219,"date":"2014-08-12T19:28:11","date_gmt":"2014-08-13T02:28:11","guid":{"rendered":"http:\/\/tubetime.us\/?p=219"},"modified":"2014-08-12T19:28:11","modified_gmt":"2014-08-13T02:28:11","slug":"flea-market-find-dual-gun-crt","status":"publish","type":"post","link":"https:\/\/tubetime.us\/index.php\/2014\/08\/12\/flea-market-find-dual-gun-crt\/","title":{"rendered":"Flea Market Find&#8211;Dual Gun CRT"},"content":{"rendered":"<p>At the electronics flea market on Saturday, I found a 3ABP7 dual gun CRT. This one was built by DuMont, most likely intended for the 3&#8243; version of their 5&#8243; <a href=\"http:\/\/www.radiomuseum.org\/r\/dumont_la_dual_beam_oscilloscope_27.html\">Type 279 Dual Beam Oscilloscope<\/a>.<\/p>\n<p>So of course I had to fire it up. There are two sets of deflection coils, so I drove them with one deflection board and cross-wired the deflection coils to flip the image around on the second gun.<\/p>\n<p>The guns themselves have a common cathode connection and separate grids, which forces me to drive them both in parallel since my deflection board video amplifier keeps the grid at a constant potential and drives the video onto the cathode.<br \/>\n<a href=\"https:\/\/www.flickr.com\/photos\/tubetime\/14879478466\" title=\"Dual gun 3ABP2 CRT by eschlaep, on Flickr\"><img loading=\"lazy\" src=\"https:\/\/farm4.staticflickr.com\/3839\/14879478466_cbf5d81959_n.jpg\" width=\"320\" height=\"180\" alt=\"Dual gun 3ABP2 CRT\"><\/a><\/p>\n<p>Here&#8217;s a closer look at the guns. The filaments are connected in parallel so this tube uses twice the normal current.<br \/>\n<a href=\"https:\/\/www.flickr.com\/photos\/tubetime\/14899416561\" title=\"Dual gun 3ABP2 CRT by eschlaep, on Flickr\"><img loading=\"lazy\" src=\"https:\/\/farm4.staticflickr.com\/3851\/14899416561_78a8c438dd_n.jpg\" width=\"320\" height=\"180\" alt=\"Dual gun 3ABP2 CRT\"><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>At the electronics flea market on Saturday, I found a 3ABP7 dual gun CRT. This one was built by DuMont, most likely intended for the 3&#8243; version of their 5&#8243; Type 279 Dual Beam Oscilloscope. So of course I had to fire it up. There are two sets of deflection coils, so I drove them [&hellip;]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true},"categories":[1],"tags":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p80Z1r-3x","_links":{"self":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts\/219"}],"collection":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/comments?post=219"}],"version-history":[{"count":0,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/posts\/219\/revisions"}],"wp:attachment":[{"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/media?parent=219"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/categories?post=219"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tubetime.us\/index.php\/wp-json\/wp\/v2\/tags?post=219"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}