Re: LM-386 Live or Die?
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Hey Russel, Yes, those caps can be a pain. In aerospace, they over-filter everything so 10% can be junk and the noise factor stays low, coupling doesn't fit that bill of course. I build my projects in stages and test them before moving on, an artifact of my breadboarding projects. When I get home tonight if I am not too tired will get out my transmitter so it can be above my QRN level to test things. Cheers, Davey - KU9L
On Friday, May 12, 2023 at 09:20:56 AM MDT, Russell Smith via groups.io <n0qlt@...> wrote:
Davey, Do you hear a buzz when you touch pin 3 of the Lm386?? Here are a couple of things I'd look at: Check around the mute FET. Is there audio on the LM386 side? Also, coupling caps can be suspect. I ran a merry chase with a PIC-based CW decoder I build many years ago that only "kinda worked." I found with my primitive method (maybe an earphone--I don't think I had a scope then) that I had audio from the rig on one side of the cap and nada on the the other. Brand new expensive brand-name cap. I was a new ham/electronics tech then and I took it to a more advanced tech at work Nah, he shook his head. It all tested fine on the bench. He replaced the bucket with one in his stash and...voila--problem solved.? So, don't rule out weird flakiness. At another job early in my career (while I was still in school), I got stuck repairing these in-circuit test machine cards. The machines were ancient A few years (like 3) younger than me. I'll be 50 in July) and some parts were unobtanium. However, poor manufacturing processes at the plant caused the product we were testing to have big, bad issues that blue these machine cards out at an alarming rate. I could fix most of them easy enough--generally one of 3 or 4 parts (or a part related to them)-- typically, 4066 ICs or output transistors. But I had one or two in my stack NO ONE could fix. I rebuilt the entire section of one with new parts and it was still broken. I found another had a broken internal trace, but it couldn't be repaired easily with a jumper (I don't remember why now--physical constraint or something).? So, for those of you who are X-Files fans (I've be rewatching the series from the start), you know these machines might have a mind of their own! I did have a similar trouble with a mute switch, though, on another kit. The FET was out to lunch. -HRS H. Russell Smith, N0QLT???
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On Thursday, May 11, 2023 at 01:52:44 PM CDT, David Knapp via groups.io <renewables@...> wrote:
Yeah David, lucky. Today we had a blizzard so we went to the local cafe for breakfast to plan our day tomorrow & this afternoon I am stuffing parts onto my board, LOL. Davey - KU9L
On Thursday, May 11, 2023 at 03:18:22 AM MDT, David Wilcox K8WPE via groups.io <djwilcox01@...> wrote:
Davey,? You lucky guy. The only camp ground I live and work at is our retirement home on a nice lake. ?I am 78 and my wife is 71 and our handy man petered out on us this year so we are doing ourselves all the lawn maintenance and putting the boats, etc., in for the grands that don¡¯t come very often. ?Hope to get out in the yard soon and do some portable work as all this raking and hauling is making us both ?achey and tired before our time¡.. ha! ?Very little noise at out QTH since the AM radio business is less profitable and the AM radio station across the lake sold their property and took down their 4 tower directional antenna on 1310 (3 x 1310 is 3930 kHz). ?1330 kHz is a great frequency for statewide nets that I participate in occasionally. I have often thought of offering my handyman services to a camp ground in the winter but it has never happened. ?My wife keeps me busy enough. ?Fifty years together. She got a new ring and I got a wad of money for Dayton¡. Fair trade in this household and I don¡¯t wear jewelry.? Dave K8WPE since 1960 David J. Wilcox¡¯s iPad On May 11, 2023, at 12:24 AM, David Knapp via groups.io <renewables@...> wrote:
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David Knapp