{"id":193,"date":"2008-09-28T00:36:33","date_gmt":"2008-09-27T19:06:33","guid":{"rendered":"http:\/\/brainstorms.in\/?p=193"},"modified":"2008-09-28T14:33:57","modified_gmt":"2008-09-28T09:03:57","slug":"bitx-progressing","status":"publish","type":"post","link":"https:\/\/brainstorms.in\/?p=193","title":{"rendered":"Bitx Progressing"},"content":{"rendered":"<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"http:\/\/brainstorms.in\/images\/bitx_20.jpg\" alt=\"\" width=\"450\" height=\"360\" \/><\/p>\n<p style=\"text-align: center;\">The Bitx completed<\/p>\n<p><a href=\"http:\/\/brainstorms.in\/?cat=7\">My bitx project <\/a>has been lying dormant for a couple of  months now. I completed wiring about 2 months back. The transmitter was working properly. But the receiver was  not receiving anything . When I tried to increase volume,  it started howling.  After initial testing,  I  became  QRL with lot of other activities.   This weekend I decided to look at bitx board again. I carefully rechecked all stages and found out that I had made 2 mistakes in wiring components , a 22 ohms resistor was in the place of 220 ohm and at another place I put a 1k instead of 100 ohm. After correcting the mistakes I fired up the receiver , I could hear some CW transmission around 14.01Mhz. When I increased the volume, the audio stage was howling. I decided to discard the audio stage and build a new one. I bought a small audio module form local market for Rs 25 and fixed it to the board. Now the audio is clean even when the volume is maximum.  I am still not satisfied with the sensitivity of the receiver.  I made the following measurements on various transistors today.  The table of the voltages on transistors  are given below. The  transistors numbers are based on Bitx V3 diagram by OM vu2wmj Rahul.<\/p>\n<p style=\"text-align: center;\">BitX20 Voltage chart<\/p>\n<p>Voltages on Receiver Chain\u00a0 Supply voltage 12 V.\u00a0 Transistor used 2N3904<\/p>\n<div>\n<table id=\"mjyc\" class=\"zeroBorder\" style=\"height: 124px;\" border=\"0\" cellspacing=\"0\" cellpadding=\"3\" width=\"462\">\n<tbody>\n<tr>\n<td width=\"25%\">Transistor<\/td>\n<td style=\"text-align: center;\" width=\"25%\">Emitter<\/td>\n<td width=\"25%\">Base<\/td>\n<td width=\"25%\">Collector<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q1<\/td>\n<td width=\"25%\">1.64<\/td>\n<td width=\"25%\">2.38<\/td>\n<td width=\"25%\">8.22<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q2<\/td>\n<td width=\"25%\">1.8<\/td>\n<td width=\"25%\">2.5<\/td>\n<td width=\"25%\">8.14<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q3a<\/td>\n<td width=\"25%\">0<\/td>\n<td width=\"25%\">.6<\/td>\n<td width=\"25%\">4.46<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q3<\/td>\n<td width=\"25%\">4.04<\/td>\n<td width=\"25%\">4.76<\/td>\n<td width=\"25%\">10.6<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q4<\/td>\n<td width=\"25%\">0<\/td>\n<td width=\"25%\">.6<\/td>\n<td width=\"25%\">2.04<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p style=\"text-align: center;\">\n<p>Voltages on Transmitter Chain, Supply Voltage 12V<\/p>\n<div>\n<table id=\"ijii\" class=\"zeroBorder\" style=\"height: 146px;\" border=\"0\" cellspacing=\"0\" cellpadding=\"3\" width=\"463\">\n<tbody>\n<tr>\n<td width=\"25%\">Transistor<\/td>\n<td width=\"25%\">Emitter<\/td>\n<td width=\"25%\">Base<\/td>\n<td width=\"25%\">Collector<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q10<\/td>\n<td width=\"25%\">1.72<\/td>\n<td width=\"25%\">2.33<\/td>\n<td width=\"25%\">7.7<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q11<\/td>\n<td width=\"25%\">1.5<\/td>\n<td width=\"25%\">2.1<\/td>\n<td width=\"25%\">7.3<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q12<\/td>\n<td width=\"25%\">1.31<\/td>\n<td width=\"25%\">1.95<\/td>\n<td width=\"25%\">6.2<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q13<\/td>\n<td width=\"25%\">1.41<\/td>\n<td width=\"25%\">1.96<\/td>\n<td width=\"25%\">6.4<\/td>\n<\/tr>\n<tr>\n<td width=\"25%\">Q14<\/td>\n<td width=\"25%\">2.2<\/td>\n<td width=\"25%\">2.9<\/td>\n<td width=\"25%\">9.5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>I think I need to verify the voltages with some other builder.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Bitx completed My bitx project has been lying dormant for a couple of months now. I completed wiring about 2 months back. The transmitter was working properly. But the receiver was not receiving anything . When I tried to increase volume, it started howling. After initial testing, I became QRL with lot of other&hellip; <a href=\"https:\/\/brainstorms.in\/?p=193\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Bitx Progressing<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,7],"tags":[],"class_list":["post-193","post","type-post","status-publish","format-standard","hentry","category-electronics","category-ham-radio"],"_links":{"self":[{"href":"https:\/\/brainstorms.in\/index.php?rest_route=\/wp\/v2\/posts\/193","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/brainstorms.in\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/brainstorms.in\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/brainstorms.in\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/brainstorms.in\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=193"}],"version-history":[{"count":0,"href":"https:\/\/brainstorms.in\/index.php?rest_route=\/wp\/v2\/posts\/193\/revisions"}],"wp:attachment":[{"href":"https:\/\/brainstorms.in\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=193"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/brainstorms.in\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=193"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/brainstorms.in\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=193"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}