{"id":3763,"date":"2025-01-06T19:56:00","date_gmt":"2025-01-06T08:56:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2025\/01\/06\/a-tale-of-woe-troubleshooting-my-15-10-rig-in-the-dominican-republic\/"},"modified":"2025-07-22T18:00:59","modified_gmt":"2025-07-22T08:00:59","slug":"a-tale-of-woe-troubleshooting-my-15-10-rig-in-the-dominican-republic","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2025\/01\/06\/a-tale-of-woe-troubleshooting-my-15-10-rig-in-the-dominican-republic\/","title":{"rendered":"A Tale of Woe &#8212; Troubleshooting my 15-10 Rig in the Dominican Republic"},"content":{"rendered":"<p><iframe loading=\"lazy\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen=\"\" frameborder=\"0\" height=\"247\" referrerpolicy=\"strict-origin-when-cross-origin\" src=\"https:\/\/www.youtube.com\/embed\/gT-2b8h6YIo?si=hxQ2a8NmSDveMPhn?rel=0\" title=\"YouTube video player\" width=\"440\"><\/iframe><\/p>\n<div><\/div>\n<div><b>&#8212; Problem first showed up as a low level oscillation in the background. Annoying. <\/b><\/div>\n<div><b>&#8212; I suspected the simple AF amp from the TJ DC RX project was oscillating. Wasted a lot of time. <\/b><\/div>\n<div><b>&#8212; Isolated the problems by cutting off all of the RF input to the SBL-1 mixer. <\/b><\/div>\n<div><b>&#8212; While watching the carrier osc signal, noticed that the hum appeared as the waveform got fuzzy. <\/b><\/div>\n<div><b>&#8212; I had used the osc\/product detector circuit from the BITX 20. <\/b><\/div>\n<div><b>&#8212; I had added an amplifier stage to get the signal to higher level. But it was poorly designed. <\/b><\/div>\n<div><b>&#8212; After some struggle, I decided to rebuild the osc\/mixer board. <\/b><\/div>\n<div><b>&#8212; Redesigned amplifier stage using LTSpice. <\/b><\/div>\n<div><b>&#8212; Changed from an SBL-1 mixer to a singly balanced mixer like in the BITX 20. <\/b><\/div>\n<div><b>&#8212; This worked well. Hum disappeared. <\/b><\/div>\n<div><b>&#8212; But I had neglected to put the .001 uF cap to ground from the AF port! Thus the cartoon! <\/b><\/div>\n<div><b>&#8212; This is a very important cap. Circuit was a lot more balanced with this cap in place. <\/b><\/div>\n<div><b>&#8212; Noiticed that output on 10 was only about 25 watts PEP, while on 15 it was around 100. <\/b><\/div>\n<div><b>&#8212; Checked input to final amps. Input on 10 was a lot lower. <\/b><\/div>\n<div><b>&#8212; Tweaked the 10 meter bandpass filter and got the output on 10 up to about 80 watts. <\/b><\/div>\n<div>\n<div class=\"separator\" style=\"clear: both; text-align: center;\"><a href=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2025\/01\/IMG_9005202.jpg\" imageanchor=\"1\" style=\"margin-left: 1em; margin-right: 1em;\"><img loading=\"lazy\" decoding=\"async\" border=\"0\" data-original-height=\"3594\" data-original-width=\"1144\" height=\"640\" src=\"https:\/\/www.homebrewradio.us\/blog\/wp-content\/uploads\/2025\/01\/IMG_9005202.jpg\" width=\"204\" \/><\/a><\/div>\n<div class=\"separator\" style=\"clear: both; text-align: center;\">Re-Built board for carrier osc\/BFO and mixer for TX and RX<\/div>\n<p><b><br \/><\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div>\n<p><b><br \/><\/b><\/div>\n","protected":false},"excerpt":{"rendered":"<p>&#8212; Problem first showed up as a low level oscillation in the background. Annoying. &#8212; I suspected the simple AF amp from the TJ DC RX project was oscillating. Wasted a lot of time. &#8212; Isolated the problems by cutting off all of the RF input to the SBL-1 mixer. &#8212; While watching the carrier &hellip; <a href=\"https:\/\/www.homebrewradio.us\/blog\/2025\/01\/06\/a-tale-of-woe-troubleshooting-my-15-10-rig-in-the-dominican-republic\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;A Tale of Woe &#8212; Troubleshooting my 15-10 Rig in the Dominican Republic&#8221;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":3764,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[123,28,19,12,25],"tags":[],"class_list":["post-3763","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-15-10-transceiver","category-bitx20","category-dominican-republic","category-tj-dc-rx","category-troubleshooting"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/3763","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=3763"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/3763\/revisions"}],"predecessor-version":[{"id":3765,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/3763\/revisions\/3765"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/3764"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=3763"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=3763"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=3763"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}