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QMX internal speaker mod
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I finished building my QMX last week and made a few cw qso's with it. It is indeed a well thought, high quality kit that I really enjoyed working on. Thanks Hans and the QRP Labs team!
Although I always use earphones when operating outdoor, I want to have an internal speaker within those tiny ultra portable rigs for self-containedness, which at least will be useful for code practice in my room, on my bed, etc. I did the mod on my Youkits HB-1B sometime back, and this weekend I tried the same mod on my newly built QMX. LM386 circuit board attached underneath the QMX control board 10mm dia * 3.5mm depth 0.5w 8ohm speaker attached next to the microphone QMX mainboard preparation for 12v+ and audio out Control board + speaker + amp assembled with the mainboard The parts are found from Amazon or eBay. The attached video shows how it sounds, and it is louder than that is captured in the video, but anyways this tiny internal speaker cannot replace the earphones or a good amplified external speaker. The mod was just for fun and the extra peace in my mind. :-) 73, Yoon KM6KJI |
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I like the way you think -mike/w1mt On Sun, Sep 10, 2023 at 18:58 Yoon KM6KJI via <yoonh.choi=[email protected]> wrote: I finished building my QMX last week and made a few cw qso's with it. It is indeed a well thought, high quality kit that I really enjoyed working on. Thanks Hans and the QRP Labs team! |
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Sorry for the third post.? Yoon, have you considered drilling a similar (maybe a little larger) hole like the Mic has in the QMX top cover (and make the hole black with a Sharpie)???? Looks like there happens to be an unencumbered area right over where the sound port of your speaker is located.? Would not even interfere with the VFO functions lasered (printed) info nearby.
Did you connect the amp input to headphone jack X401 pin 4 or 5 so plugging anything into the jack disconnects your internal amp input?? This to me would seem to be the way to do it. I may just have to do this mod!? Again, nice work. 73, Robert |
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Robert,
Yes that's the LM386 module I bought from Amazon. I didn't remove or replace the capacitor, but utilized it as the support for the control board with a plastic nut glued on the cap. Because I pursue reversible mods, I didn't add a new hole for the speaker. I don't think it would make a big difference but you may try. For wiring to the audio jack, initially I used only pin 5, and later I added a jumper between pin 4 and 5 because I remembered the manual saying that the left and the right audio channels are separate. Plugging in a earphone will disconnect the audio out to the amp of course, to mute the speaker. Thanks, Yoon KM6KJI |
Dale Hardin KS4NS
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