http://groups.yahoo.com/group/Sangean803/ Sangean 803 A / Radio Shack DX 440 Tue, 05 Jan 2010 02:03:30 GMT cybercat http://groups.yahoo.com/group/Sangean803/message/2963 http://groups.yahoo.com/group/Sangean803/message/2963 Let's try simple and low cost first. Connect a balun (matching transformer) that the cable TV companies use between the external antenna jack (the 75 ohms Mon, 04 Jan 2010 20:04:37 GMT Ray http://groups.yahoo.com/group/Sangean803/message/2962 http://groups.yahoo.com/group/Sangean803/message/2962 Hi All; I am thinking of selling my DX440. Haven't even turned it on in the last few years. Works perfectly or maybe I should say worked perfectly being as I Mon, 04 Jan 2010 19:59:37 GMT Lawrence http://groups.yahoo.com/group/Sangean803/message/2961 http://groups.yahoo.com/group/Sangean803/message/2961 Build a new set from scratch? Nah...for now I'll stick with the radio's 75-ohm connector. Was just a thought. I knew that certain types of wires have their own Mon, 04 Jan 2010 19:56:59 GMT Andy - KU4XR http://groups.yahoo.com/group/Sangean803/message/2960 http://groups.yahoo.com/group/Sangean803/message/2960 Larry:   I believe you're right. I have never used an external antenna on my Sangean. I have usually just capacitively coupled the radio to a larger antenna, Mon, 04 Jan 2010 09:51:43 GMT Bob Yorston http://groups.yahoo.com/group/Sangean803/message/2959 http://groups.yahoo.com/group/Sangean803/message/2959 Hi Larry - Delving into the set at that point probably won't help much,  as on the AM side of it, you first go to some diode switching, then the RF Mon, 04 Jan 2010 09:24:00 GMT Lawrence http://groups.yahoo.com/group/Sangean803/message/2958 http://groups.yahoo.com/group/Sangean803/message/2958 Hello Andy, A lot of that info was helpful, particularly the paragraph dealing with the impedance & radio circuitry. However, one thing you said (after that) Mon, 04 Jan 2010 03:53:27 GMT Andy - KU4XR http://groups.yahoo.com/group/Sangean803/message/2957 http://groups.yahoo.com/group/Sangean803/message/2957 HI Lawrence:   Well here's my stab at the subject. I am not an antenna designer, I am an antenna experimenter. I look at theory, which by the way always works Sun, 03 Jan 2010 23:11:59 GMT drdokman http://groups.yahoo.com/group/Sangean803/message/2956 http://groups.yahoo.com/group/Sangean803/message/2956 Hi: I have a Sangean 803A that powers up but I can't get to play. I do believe I fried transistors in the power supply circuit. I can see one that is Sun, 03 Jan 2010 17:20:31 GMT Lawrence http://groups.yahoo.com/group/Sangean803/message/2955 http://groups.yahoo.com/group/Sangean803/message/2955 Thanks Bob and Andy for your last posts. (Zener diode & the DOS inductance calc). I typed a reply that day, but apparently Yahoo had a seizure & it never went Sun, 27 Dec 2009 20:40:59 GMT Bob Yorston http://groups.yahoo.com/group/Sangean803/message/2954 http://groups.yahoo.com/group/Sangean803/message/2954 Hi Larry - The main thing is - you've got a loop which works. Unfortunately, I gather that you can;t vary its tuning. How aboutn takin a 9V battery, a 1 meg Sun, 27 Dec 2009 17:48:19 GMT Lawrence http://groups.yahoo.com/group/Sangean803/message/2953 http://groups.yahoo.com/group/Sangean803/message/2953 Thanks again Bob. I plan on getting more wire & add windings to my loop. For increased L, while still using the fixed caps. I formerly used 4 to 6 windings on Sun, 27 Dec 2009 07:47:23 GMT Bob Yorston http://groups.yahoo.com/group/Sangean803/message/2952 http://groups.yahoo.com/group/Sangean803/message/2952 Hi Larry - OK, you've got a loop. As the loop doesn't go down to a low enough frequency, you've put more C across it. Fair enough, but it's normally better to Sat, 26 Dec 2009 17:46:36 GMT Lawrence http://groups.yahoo.com/group/Sangean803/message/2951 http://groups.yahoo.com/group/Sangean803/message/2951 Bob, what I basically hope to do is make my own preselector/impededance matching unit. The schematic recommended by LF Engineering shows selectable inductors Sat, 26 Dec 2009 13:13:37 GMT Bob Yorston http://groups.yahoo.com/group/Sangean803/message/2950 http://groups.yahoo.com/group/Sangean803/message/2950 Hi Larry - Sorry, you've lost me somewhat - are you trying to put inductors in series with your loop to increase the L? Any form of inductor, whether it be a Sat, 26 Dec 2009 08:56:07 GMT Lawrence http://groups.yahoo.com/group/Sangean803/message/2949 http://groups.yahoo.com/group/Sangean803/message/2949 Bob, Thank you for the encouragement! My plans are in this works for this. Right now I continue to get good results just placing(combinations of) fixed caps to