{"id":9034,"date":"2025-02-04T14:09:00","date_gmt":"2025-02-04T03:09:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2025\/02\/04\/mr-carlson-restores-a-bc-348-but-40-meters-sounds-very-weak-why\/"},"modified":"2025-07-22T18:00:59","modified_gmt":"2025-07-22T08:00:59","slug":"mr-carlson-restores-a-bc-348-but-40-meters-sounds-very-weak-why","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2025\/02\/04\/mr-carlson-restores-a-bc-348-but-40-meters-sounds-very-weak-why\/","title":{"rendered":"Mr. Carlson Restores a BC-348 &#8212; But 40 Meters Sounds Very Weak.  Why?"},"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\/p9pMvDN7kMk?si=MV4i9pjSgcDPoZWR?rel=0\" title=\"YouTube video player\" width=\"440\"><\/iframe><\/p>\n<div><\/div>\n<div><b>Mr. Carlson mentions that he is a ham radio AMer. He is also on SSB, but AM is, he says, his preferred mode. FB. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>I got a real chuckle about the MVC switch position on the front panel. &#8220;Manual Volume Control&#8221; like &#8220;Manual Gain Control.&#8221; I thought I had invented this term. You know, &#8220;real hams control their gain manually.&#8221; This is why Farhan never put AGC in the BITX20. But it seems the Army Air Corps was way ahead of me with the BC-348. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>Mr. Carlson makes it sound (!) like the Dynamotors are a thing of the past. Not true. Every Saturday morning I listen to the Old Miltary Radio Net and hear a number of Dynamoters spinning in the background. One belongs to Buzz W3EMB who uses a BC-348. Buzz has an SDR attached to the IF of his BC-348, which I think is an admirable mix of the old and the new. Those BC-348s are, after all, quite old. WWII old &#8212; like 85 years old. And still working. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>Paul has a good discussion of the importance of short lead length, and of mounting shielded capacitors properly, and of the usefullness of a good groundplane under the capacitor. Go Manhattan boards! Paul&#8217;s presentation on how to identify the outside foil of a capacitor was very good, but I was wondering if you could also find out by using a file to remove some of the yellow insulation, then test with a DMM to see which terminal is connected to the foil. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>&#8220;Lots of times you have to add solder to remove solder.&#8221; Indeed. <\/b><\/div>\n<div><\/div>\n<div><b>The importance of testing for BOTH capacitance and leakage. Yes. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>But why bother with &#8220;period correct&#8221; internal wiring harnesses, when you have already put a bunch of modern caps in there? I mean, I&#8217;m in favor of the re-capping, but this seems inconsistent with the need for &#8220;period correct&#8221; internal wiring harnesses. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>When Paul first fired up the receiver, I was hoping he would disconnect the antenna to see how much band noise was getting through. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>When Paul got to the IF alignment, he spoke of the dangers of working on energized high-voltage gear. I had been thinking about getting a BC-348 myelf, but Paul&#8217;s comments reminded me of why this is probably not a good idea for me. Paul&#8217;s comments about &#8220;knowing where your hands are&#8221; is on target. &#8220;One hand behind the back, &#8221; is a good rule for this kind of energized testing &#8212; this will help prevent current from a mishap from flowing through your chest. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>I may have more comments later. Off to the beach now. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>Back from the beach: <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>&#8220;Contrary to popular belief, the simpler the receiver, the better they hear.&#8221; Amen Mr. C. <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>Paul&#8217;s heroic cleaning of the 915 kc crystal made me feel like a wimp for not having tried to do this with some &#8220;bad&#8221; 455 kc rocks I was given while trying to build the Mate for the Mighty Midget receiver. I may go back to those crystals and try to clean them as Mr. C did. <\/b><\/div>\n<div><\/div>\n<div><b>The grand finale of this 2.5 hour video was, as expected, a demonstration of how good it sounds. But unfortunately it did not sound good. Paul tuned through the 40 meter band and I heard NO CW signals. I didn&#8217;t even hear FT8. There were a few anemic SSB signals and, as he reached the upper portion of the band some very weak AM broadcast signals. I didn&#8217;t even hear CHU Canada&#8217;s time signal. Huh? Why? Our very simple homebrew Direct Conversion receiver sounds a LOT better than that. I mean look at the sweep of 40 meters that I did using only a simple dipole: <a href=\"https:\/\/soldersmoke.blogspot.com\/2024\/12\/an-evening-bandscan-on-40-meters-using.html\"> https:\/\/soldersmoke.blogspot.com\/2024\/12\/an-evening-bandscan-on-40-meters-using.html<\/a> Why is there such a big difference in performance? <\/b><\/div>\n<div><b><br \/><\/b><\/div>\n<div><b>Could it be the antenna that Paul was using? He was on what he calls the 369 antenna. Could there be a problem in the receiver? Could it be band conditions? <\/b><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Mr. Carlson mentions that he is a ham radio AMer. He is also on SSB, but AM is, he says, his preferred mode. FB. I got a real chuckle about the MVC switch position on the front panel. &#8220;Manual Volume Control&#8221; like &#8220;Manual Gain Control.&#8221; I thought I had invented this term. You know, &#8220;real &hellip; <a href=\"https:\/\/www.homebrewradio.us\/blog\/2025\/02\/04\/mr-carlson-restores-a-bc-348-but-40-meters-sounds-very-weak-why\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Mr. Carlson Restores a BC-348 &#8212; But 40 Meters Sounds Very Weak.  Why?&#8221;<\/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":[42,130,69,233,243,101],"tags":[],"class_list":["post-9034","post","type-post","status-publish","format-standard","hentry","category-40-meters","category-am","category-antennas","category-carlson-mr","category-military-radios","category-tubes"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/9034","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=9034"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/9034\/revisions"}],"predecessor-version":[{"id":11156,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/9034\/revisions\/11156"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=9034"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=9034"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=9034"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}