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QCX 40 Woes

Mike Corner All Messages By This Member #33287 Just finished my QCX 40 kit and it went together well. Came right up with good alignment and output at 12-16v. Problem is cw sounds terrible through the headphones/speaker. I get a loud click at the beginning and end with about a one second delay on semi-qsk. There is no sideband on anything above 20wpm on full qsk.Rechecked output and alignment which is good. Kinda stumped at this point.
n4qa at_hotmail.com #33289 Hi Mike. I get that a lot when my rig, PC etc try to become part of my antenna system, especially when using an external 'amplified speaker'. Could you describe your antenna & feedline...and any audio processing components. 72 /73, Bill, N4QA
Charles W. Powell All Messages By This Member #33306 开云体育 Mike, The first question is what revision of the board do you have? ?If it is 1-3 you need to replace the electrolytics C21 & C22 with 0.1 uF ceramic caps. ?That has worked on 5 radios I have built 72, Chas - NK8O toggle quoted message Show quoted text On Apr 7, 2019, at 12:42 PM, Mike Corner via Groups.Io <mikescorner@...> wrote: Just finished my QCX 40 kit and it went together well. Came right up with good alignment and output at 12-16v. Problem is cw sounds terrible through the headphones/speaker. I get a loud click at the beginning and end with about a one second delay on semi-qsk. There is no sideband on anything above 20wpm on full qsk.Rechecked output and alignment which is good. Kinda stumped at this point.
Brien Pepperdine #33307 开云体育 PCB revision 4 on Hans' QRP Labs page states that they have been replaces with 1 uf ceramic.... you have gone with .1 uf? ceramic. Any real difference?...? I have not done this YET... but I did point out the change to Mike earlier today... as I did with a couple guys in my club who are just getting around to their kits that were sitting for a while. tnx Brien VE3VAW toggle quoted message Show quoted text ---------- Original Message ---------- From: "Charles W. Powell via Groups.Io" <doctorcwp@...> Date: April 7, 2019 at 5:15 PM Mike, The first question is what revision of the board do you have? ?If it is 1-3 you need to replace the electrolytics C21 & C22 with 0.1 uF ceramic caps. ?That has worked on 5 radios I have built 72, Chas - NK8O On Apr 7, 2019, at 12:42 PM, Mike Corner via Groups.Io < mikescorner@...> wrote: Just finished my QCX 40 kit and it went together well. Came right up with good alignment and output at 12-16v. Problem is cw sounds terrible through the headphones/speaker. I get a loud click at the beginning and end with about a one second delay on semi-qsk. There is no sideband on anything above 20wpm on full qsk.Rechecked output and alignment which is good. Kinda stumped at this point. ? ?
Charles W. Powell All Messages By This Member #33308 开云体育 On the earlier kits, 0.1 uF works fine. ?On the Rev 4, it needs to be higher. ?If you use 0.1 uF on a rev 4 board you will get very little audio. ?Just my 2? and experience with it. 72, Charles - NK8O toggle quoted message Show quoted text On Apr 7, 2019, at 4:45 PM, Brien Pepperdine <brianpepperdine@...> wrote: PCB revision 4 on Hans' QRP Labs page states that they have been replaces with 1 uf ceramic.... you have gone with .1 uf? ceramic. Any real difference?...? I have not done this YET... but I did point out the change to Mike earlier today... as I did with a couple guys in my club who are just getting around to their kits that were sitting for a while. tnx Brien VE3VAW ---------- Original Message ---------- From: "Charles W. Powell via Groups.Io" <doctorcwp@...> Date: April 7, 2019 at 5:15 PM Mike, The first question is what revision of the board do you have? ?If it is 1-3 you need to replace the electrolytics C21 & C22 with 0.1 uF ceramic caps. ?That has worked on 5 radios I have built 72, Chas - NK8O On Apr 7, 2019, at 12:42 PM, Mike Corner via Groups.Io < mikescorner@...> wrote: Just finished my QCX 40 kit and it went together well. Came right up with good alignment and output at 12-16v. Problem is cw sounds terrible through the headphones/speaker. I get a loud click at the beginning and end with about a one second delay on semi-qsk. There is no sideband on anything above 20wpm on full qsk.Rechecked output and alignment which is good. Kinda stumped at this point. ? ?
John Pagett G4YTJ All Messages By This Member #33309 The original QCX used 10uF capacitors. Someone in an earlier thread showed that these were the cause of key clicks (to be correct, they were passing the clicks caused by the offset on the sidetone signal). In his investigation I think he replaced the 10uF with 100nF. In a later thread, someone else pointed out that 100nF was small enough to attenuate the wanted audio. I can't recall who these contributors were. So 1uF is the Goldilocks value. Not too large, not too small! John G4YTJ Sent from my iPad

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